ASTB Mechanics Comprehension Questions Flashcards

The wheels are connected by a belt. As the wheel on the left makes one revolution, the wheel on the right makes less than one revolution exactly one revolution more than one revolution more than one revolution If the wheel on the left turns clockwise, in which direction does the wheel on the right turn? Clockwise Counterclockwise Counterclockwise A woman sits in a dragster at the beginning of a race. As the light turns green, she steps on the accelerator. At the moment the dragster begins to accelerate what is her weight pushing into the seat relative to while the car was stationary? Less than stationary The same as stationary More than while stationary More than while stationary All the gears in the system are moving and Gear 1 rotates clockwise. What other gears in the system also rotate clockwise? 2 and 4 2 and 5 3 and 5 3 and 5 In which case is less force needed to move weight (W) up the ramp? A B The force is the same in each case. A If each pendulum is released from the position shown, which pendulum requires the longest amount of time to complete one swing? A B The times are equal B The voltage drop or potential difference is greater across which resistor? Ra Rb It is the same across either resistor It is the same across either resistor If the large portion has 3 times the surface area of the small piston, how far must the small piston be pushed down to raise the large piston 1 inch? 1/2 inch 1 inch 3 inches 3 inches If the three squad leaders are to stay on line, which of them must turn the most slowly? A B C C In order to balance the scale above, the fulcrum should be moved toward A toward B in either directions toward B If the scale was balanced before u moved the fulcrum, which of the balls is more dense? Ball A Ball B They have the same density Ball B Where would it be best to hold a pruners' handles while trying to cut a branch? A B It does not matter B If the current leaves the battery in the direction shown in the diagram, what is the direction of the current in resistor X? A B There is no current in the resistor A The voltage drop is greater across which resistor Rx Ry It is the same across either resistor Rx Where is the current greater in the circuit? Greater at A than B Greater at B than A The same at A and B The same at A and B X, which has a negative charge, is positioned between a positive charge (A) and a negative charge (B). In which direction will X move? A B Remain where it is A In a stream, water flows through narrow and wide sections. In which sections does the water flow fastest? Narrow section Wide section The same through either section Narrow section At what point is the velocity of a bullet fastest? When it leaves the muzzle When it reaches the top of its arc When it hits the target When it leaves the muzzle The rate of heat exchange is faster between an ice cube and 100° glass of water an ice cube and 40° glass of water none of the above an ice cube and 100° glass of water If two glasses of water 40° and glass A was 1/2 full whle glass B was 3/4 full, which glass would melt the more ice in a given amount of time A B They would melt an equal amount of ice B Did you read a mechanical comprehension hand out? No, but I will now. No! What hand out? Yes, and I understood everything. Yes, and I understood everything. If the large pistion has 2 times the surface area of the small piston, how far must the large piston be pushed down to raise the small piston 1 inch? 1 inch 2 inches 1/2 inch 1/2 inch When the wheels X are turned at the same speed, which turns wheels Y faster? Wheel X1 Wheel X2 They turn wheels Y at the same speed Wheel X1 Imagine if wheels X where the front sprocket of a bicycle and wheels Y the rear sprocket. Which system would be hardest to pedal up a hill? System A System B They would have the same difficulty System A If wheel X1 is exactly twice the size wheel Y1, and wheel X1 is turned one time, how many times will wheel Y turn? One turn Two turns One half turn Two turns In system A, as wheel X1 makes one revolution, point A travels a greater distance than point B travels a smaller distance than point B travels the same distance as point B travels the same distance as point B Above is a cross section of a wing. Air travels over it and under it. As the wing moves through the air speed relative to the foil is greater above the wing below the wing the same above and below the wing greater above the wing When the plug in the tube is removed, water flows into the tube out of the tube neither way into the tube For which position of the weight is the tension on the string at point X greater? A B It is the same for each position B When is it more difficult to hold an inflated beach ball under water? Close to the surface Down deep The difficulty is the same at either depth Down deep When does a beach ball seem more buoyant? Close to the surface Down deep The buoyancy is the same at either depth Down deep Which weight exerts less pull on the horizontal bar from which the weights hang by strings? A B Each weight exerts the same pull on the bar A A submarine is traveling through the ocean when its outer hull cracks and air pushes out of its lower right side. In which direction must the rudder be turned to ensure the submarine remains on its heading? A B A A submarine is traveling through the ocean when its outer hulls cracks and air pushes out its lower right side. In which direction must the submarine be turned to ensure the submarine remains on its heading towards the port towards the starboard towards the starboard If the board to the left was placed in water, in what orientation would it float? A higher than B B higher than A Perfectly level B higher than A If two resistors and a battery are arranged in each of the above circuits, which circuit arrangement has greater resistance? Circuit A Circuit B They have the same resistance Circuit A The lever above is anchored just to the left of point A. If one were to raise it one inch measured from point A to the ground, point B would rise less than one inch one inch more than one inch more than one inch In which case is more force needed to raise the weight? A B The force is the same in each case A Which system requires more rope to be pulled to lift the weight the same distance? A B They require the same amount of rope B Which pendulum takes less time to make one swing? A B Each takes the same time to make one swing A If pendulum A was the same length as pendulum B, which pendulum would take more time to make one swing? A B Each would take the same time to make one swing Each would take the same time to make one swing Newton's First Law An object in motion will stay in motion, object at rest will stay in motion at rest equilibrium at rest Newton's Second Law Force = Mass * Gravity Acceleration Velocity Speed Acceleration Newton's Third Law For every action there is a) an equal and opposite reaction b) a varied response c) multiple reactions a) an equal and opposite reaction Speed of conduction, which occurs in solids and stationary liquids a) creates more heat across multiple objects b) moves the lower temperature from one solid to the other c) depends on the temperature difference c) depends on the temperature difference Butcher Knives, Axes, Nail Cutters, are examples of Levers Pulleys Wedges Screws Wedges This device is typically used to measure wires, spheres, shafts and blocks. Micrometer Multimeter Tape Measure Micrometer Compressing air in a closed place will _______ the volume and ______ the pressure decrease, decrease decrease, increase increase, raise increase, increase decrease, increase Bernoulli's principal applies to liquids applies to air involves flow and pressure all of the above all of the above This class of lever is like your everyday crowbar. The fulcrum is in the middle with the resistance force, the load, on one end and the effort force on the other. An example of this would be a seesaw. First class lever Second class lever Third class lever First class lever On this class lever, the fulcrum is on the end, the resistance force, the load, is in the middle,and the effort is at the other end. An example of this would be a wheelbarrow. First class lever Second class lever Third class lever Second class lever On this class lever, the fulcrum is on the end of one side, the effort force is in the middle, and the resistance force, the load, is at the the top. An example of this would be a baseball bat. First class lever Second class lever Thrid class lever Third class lever The formula for force is mass times acceleration The maximum weight, W, that can be lifted as shown with a pull of 100 lbs is 100 lbs 200 lbs 300 lbs 200 lbs A 5 kg wad of clay is tied to the end of a string. A 300 gm copper moving horizontally is embedded into the clay and causes the clay and ball to rise to a height of 0.2 m. The intial velocity v¹ of the ball is nearly 6.3 m/s 7.3 m/s 8.3 m/s 8.3 m/s Which exerts a larger force over a distance? A small force over a long distance A large force over a short distance A small force over a long distance The formula for Work is Force x distance The formula for Efficiency is Workout/Workin , since friction causes inefficiency. The fraction is never greater than 1. A force acting on a surface is called pressure, and is calculated by Pressure = Force / Area Can be used for fluid pressure and atmospheric pressure An observer standing on the ground sees you running 55 mph. If you were running towards the caboose, what would the velocity be? 45 mph 50 mph 52 mph 55 mph 45 mph A 300 lb weight rests on a hydraulic surface with an area of 376 square inches (2 square ft). What force is needed to act upon the smaller surface having an area of 36 square inches (six by six)? 28.8 lbs Pressure in liquids that are not moving is called ________ pressure, and is caused by ______. If fact, as you go twice as deep, the pressure will be ______ as much. hydrostatic/gravity/increases hydraulic/force/increases hydraulic/gravity/decreases hyydrostatic/force/decreases hydrostatic/gravity/increases ____________ pressure is caused by the weight of the air between the earth's surface and space. Hydraulic Atmospheric Hydrostatic Atmospheric Energy travels from objects of different temperature in the form of _____ through the process of conduction and convection and radiation. Heat _________ occurs in liquid and gases by calculating currents caused by a difference in density. All objects radiate heat; most of which is infared radiation that is not visible. ________ heat transfer depends on the temperature difference. The _________ are not important. Nor does it matter whether one is cold rather than hot. The heat will flow from the hot object to the cold object. The rate of heat transfer will be greater for a larger temperature difference. Convection/Radiation/Mass Radiation/Conduction/Temperature Conduction/Convection/Temperature Convection/Conduction/Temperature Radiation/Convection/Weight Conduction/Radiation/Temperature Conduction/Convection/Temperature Electrical forces are caused by electrical charges which may be positive or negative. Which of the following is true? Opposite charges repel, like charges attract. Electrical forces decrease as the distance between charge particles increases. Particles that are apart will exert greater forces on each other than particles that are close Electrical forces decrease as the distance between charge particles increases. This circuit element dissipates energy through heat Resistors Capacitors Inductors Diodes Transformers Resistors This circuit element stores electrical energy between two parallel plates Resistors Capacitors Inductors Diodes Transformers Capacitors This circuit element stores magnetic energy Resistors Capacitors Inductors Diodes Transformers Inductors This circuit element restricts current to only one direction. A semiconductor used as a rectifier. Rectifiers convert AC to DC Resistors Capacitors Inductors Diodes Transformers Diodes This circuit element is used to convert electricity from one voltage to another Resistors Capacitors Inductors Diodes Transformers Transformers The two kinds of circuits that you are responsible for are: Parallel circuits Series circuits These kinds of circuits are identifies by seeing sever circuit elements, (resistors, lights, etc.) running between parallel to each other between the positive and negative sides of the power source Parallel circuits, and in this circuit, the current gets divided between two or more elements In these kinds of circuits, all of the circuit-elements are in a row along a single wire similar to a set of Christmas lights Series circuits, and in this circuit, the voltage will continue to drop as it passes through elements until it has finally dropped to 0. What is Ohm's law? I = V/R As you follow the path of the current from the positive node away from the battery and through an element, the voltage will be the same as the bettery until the current goes through the element. After crossing a resistor there will be a _________ Voltage drop The theory behind leverage is that the longer the lever, the more ______ u produce. force torque distance weight torque, which is the product of force and distance Doubling the length of the lever-arm would ________ the torque that you apply. double The torque created by the hand must _______ the torque produced by the weight before it can be lifted. Equal Double Equal Left Side: Force = 60 lbs Distance to fulcrm = 8 ft Right Side: Force = ? Distance = 15 ft Force on the right side equals 30 lbs 32 lbs 34 lbs 36 lbs 32 lbs The _______________ of a lever is calculated by dividing the arm-length that you are applying a force by the arm-length of the resisting weight. Torque Effort Force Mechanical Advantage Mechanical Advantage What is the formula for the Mechanical Advantage of a lever? Effort Arm / Resisting Arm MA = length of effort arm ÷ length of resistance arm. What is the Mechanical Advantage of in the diagram? 1 1.44 1.88 2 1.88 You may see problems where weights and forces are acting on a single lever arm. It's possible that you'll see a combination of both. In these cases, you have to realize that torque acts in two directions. What are the two directions? They repel They attract clockwise and counterclockwise clockwise and counterclockwise Solve for the unknown force or distance 11 lbs 15 lbs 10.9 lbs 33 lbs 11 lbs A pendulums has three weights attached, each 8 in away from each other. One string is 7 in long and has a 3 lb weight. The other two strings are 5 in long. Each have a weight of 4 lbs and 8 lbs. All of them are swung from the left to the right. Which of the ff is true? a) The one with the longer string takes the longest to make one complete swing b) With the two 5 inch strings, the string with the 8 lb weight will take longer to complete a swing c) All of the above a) The one with the longer string takes the longest to make one complete swing The weight does not matter with swing time. You had two tennis balls and held them over a 10 story building, and you dropped Tennis ball A straight down while Tennis ball B was tossed horizontally first, but released them at the same time. Which would hit the ground first? A B They hit the ground at the same time They hit the ground at the same time Pushing a weight up an incline requires only a fraction of the force needed to lift the weight directly. This fraction can be found by calculating a) the ratio of the slope-length divided by the height b) the opposite leg divided by the hypotenuse of a right triangle (sin 0) c) all of the above all of the above For a height of 5, and a slope-length of 10, the Mechanical Advantage in the diagram is 10 15 1 2 2 The mechanical advantage for a pulley system a) equals the number of ropes within the system b) equals the number of pulleys within a system c) equals the maximum weight of the object e) equals the maximum effort exerted equals the number of ropes within the system Only MOVEABLE pulleys provide mechanical advantage The load is supported by how many strands of rope? 1 2 3 4 3 If the pull of the truck in the diagram is 100 lbs, what is the maximum weight of the object? 100 lbs 200 lbs 300 lbs 400 lbs 400 lbs NOTE: Also the weight will raise 1 ft for every 4 ft you pull When several ropes are in contact with the weight, they all contribute equally. Tension is defined as the force that the rope sustains internally the force that is needed to move the weight the force that the rope sustains internally the force that is needed to move the weight is equal in the rope where someone is pulling it. In the figure, there are ropes holding the weight up. Therefore they each contribute ____ of the force needed to hold the weight. 1 1/2 1/3 1/4 1/3 This specifies the change in position of a point in reference to a previous position. In simple terms, it's the difference between the initial position and the final position of an object. Displacement Movement Range Volume Displacement R = (D*R)/d is the formula for Radius Range Gear Revolutions Gear Revolutions r=(D*R)/d ; r*d=R*D Hydrometers use floats to measure specfic gravity displacement hardness of water amounts of water specfic gravity Specific gravity is the weight of a ______ compared with the weight of the water. solid gas liquid mass Liquid The liquid with the highest specific gravity will cause the float to rise higher in the glass tube the weight to sink to the bottom of the glass tube the float to maintain a balance in the center of the glass tube the float to rise higher in the glass tube Pliers and scissors are ________ levers and explain where the fulcrum of the lever is. First Class Second Class Third Class First class. The fulcrm is in the middle A nutcracker or wheelbarrow are _________ levers. First Class Second Class Third Class Second class. The fulcrum is at one end, load is in between. Tongs or tweezers are examples of _________ levers First Class Second Class Third Class Third Class Fulcrum is at one end, effort is in between. In pulley's, the smaller pulley will turn _______ than those larger than it. Faster Slower Same Speed Faster It has to "keep up" and therefore turns faster. a* d = A * D a = area d = displacement A = bigger area d = bigger displacement This is the formula for what? Mechanical Advantage in a piston An axe is classified as a wedge, which is an inclined plane first class lever second class lever third class lever inclined plane The __________ the fulcrum is from the resistance arm, the __________ amount of force that is required to lift the weight and the _______ the resistance arm will travel. closer, greater, higher farther, less, higher closer, greater, lower farther, greater, lower closer, greater, higher No electricity flows through burnt out bulbs, but a ________ can bypass it if connected on both sides. It tells you the total voltage in a circuit. voltimeter Which of the following is true: Current and Voltage varies in a parallel Current is constant in a series, voltage is not Voltage is constant in a series, current is not Current and Voltage are constant in a series Current is constant in a series, voltage is not Current * resistance = voltage The current with the _______ resistance is usually in series, because it forces the current through all resistors. greater In a 2 pulley system, the movable pulley will only move up half the distance, and spin half as much as the fixed pulley. No answer. That was a statement. What is the rpm for this wheel, that requires 2 contacts per second? 15 16 48 8 15 twice per second = 120 contacts per minute. 8 rods on wheel. 120/8=15 Heat is a form of calories motion energy pressurization energy On a standard day, at sea level, assuming static conditions, the speed of sound is 1100 ft per sec 1200 ft per sec 1300 ft per sec 1425 ft per sec 1100 ft per sec For a plane to fly, air flowing over the top of a wing creates a vaccum, while the air flowing over the bottom a) remains at approximately the same air pressure b) decreases in air pressure, allowing the wings to glide c) increases in pressure, pushing the wings upward a) remains at approximately the same air pressure The diagram depicts airflow around the wing of an aircraft. Most of the lift is caused by a) increased air pressure on the bottom side (side B) b) increased air pressure on the top side (side A) c) decreased air pressure on the bottom side (side B) d) decreased air pressure on the top side (side A) d) decreased air pressure on the top side (side A) In the diagram, which of the ff statements is not true? a) pulley 2 would spin faster than pulley 4 b) pulley 4 would spin faster than pulley 3 c) pulley 1 would spin faster than pulley 3 d) pulley 4 would spin faster than pulley 5 c) pulley 1 would spin faster than pulley 3 according to the book Which tool below is the best for cutting metal? hacksaw chainsaw rotary saw handsaw hacksaw hacksaw was designed for metal. Which of the ff is a type of lever? elevator seesaw door hinge electrical cord seesaw What is the formula of force for a lever? Fᴱ = FL dL / dᴱ Formula can be changed to Fᴱ dᴱ = FL dL Fᴱ = effort force (N, lb) FL = load force (N, lb) (note that weight is a force) dL = distance from load force to fulcrum (m, ft) dᴱ = distance from effort force to fulcrum (m, ft) Approx how much force must be exerted to lift the box? 67 lbs 100 lbs 250 lbs 258 lbs 67 lbs Fᴱ dᴱ = FL dL Fᴱ 30ft = 200lb * 10ft Fᴱ 30ft = 2000lbft Fᴱ = 2000lbft/30ft Fᴱ = 66.6666666 or 67 lb Which wrench would require more force to turn a bolt? Wrench A Wrench B No Difference None of the above Wrench A In order to move the block five feet, how many feet of rope would have to be pulled? 5 10 15 20 15 The number of cranks the crankshaft of a V-6 engine has is 2 4 6 8 6 6 pistons, 1 crank per piston Pulley A is the same size of Pulleys B and C, and twice the size of Pulley D. For each revolution made by Pulley C, how many revolutions will Pulley A make? one two three four two according to the book, two. In order to lift a 100 lb load onto a dock five feet high, using only 25 lbs of force, how long of a ramp would have to be used? 5 ft 10 ft 15 ft 20 ft 20 ft 100 / 25 = 4 4 = required MA for an inclined plane 4 * 5 feet high = 20 ft One horsepower is equal to a) 33,000 ft-pound work per min b) 150 lbs of force in an hour c) 950 psi d) 17,500 ergs a) 33,000 ft-pound work per min In the diagram, how many pulleys are turning in a clockwise direction? one two three four four according to the book, 4 Wheel A has a diameter of 10 inches. Wheel B has a diameter of 25 inches. If both revolve at the same speed, which wheel will travel the most distance in the same amount of time? Wheel A Wheel B Same distance Cannot determine Wheel B How many gears are turning in a counterclockwise direction? two three four five three If Gear 1 has revolves twice, how times will Gear 2 revolve? 1 2 3 4 1 The picture would have 2 gears, a small 10 tooth, and a large 20 tooth. In the figure, for each complete revolution of the cam, how many times will the valve open? 1 2 3 4 3 What is the area of a cylinder? 2(π r²) + (2 π r)* h In the hydraulic system depicted, the cylinder on the left has a diameter of 2 inches and the cylinder on the right has a diameter of 6 inches. If 100 lbs of force was applied to the cylinder on the left, what force would be exerted on the cylinder on the right? 300 lbs 33.3 lbs 900 lbs 450 lbs 900 lbs In the design, which tank(s) will overfill? Tank A Tank B Tank A and C Tank B and C Tank A and C Which of the following are not parts of a braking system of an automobile? discs master cylinder axel wheels axel On a braking system, the axel supports the wheel, but is not part of the braking system. The _________ provides hydraulic force to press discs (or pads) against wheels of a vehicle, making use of the force of the friction to slow (or stop) the wheels. discs pads calipers master cylinder master cylinder When a machine magnifies force, it is referred to as magnification factor mechanical advantage leverage factor efficience factor mechanical advantage A pitch is a) the distance between the threads of a screw b) the gap measurement of a spark plug c) the angle measurement of a simple lever d) one of the four basic measurements of force a) the distance between the threads of a screw When an object is at equilibrium a) its velocity does not change b) the object speeds up c) the object is at rest d) the object changes direction a) its velocity does not change Equilibrium is a) when at object is at rest b) when 2 or more forces act to cancel the effects of each other d) when the velocity speeds up b) when 2 or more forces act to cancel the effects of each other An object at equilibrium may be at rest, but not necessarily so. An example of a simple machine is a door hinge light switch can opener all of the above all of the above When a helium-filled ballon rises, the force responsible is friction air pressure buoyancy gravity air pressure In physics, power can be defined as work/time energy/efficiency leverage/mass friction/drag work/time The force acting on an object dropped from a building is buoyancy elastic recoil gravity equilibrium gravity If you remove your foot from the gas pedal in ur car, it will slowly coast to a stop. The force which causes this is friction gravity velocity magnitude friction If a driver wheel is present, the adjacent wheels will rotate according to how _________ to the center the driver wheel makes contact with them. close far close The closer to the center, the faster it will move. By increasing the length of the lever arm, the effort is increased, enabling a valve to blow off at a higher pressure. So if you... a) move the lever closer, this will cause the valve to blow up at a lower pressure b) move the lever farther, this will cause less effort c) move the weight towards the fulcrum, this will cause an increase on pressure d) move the effort closer, this will cause the valve to blow up faster b) moving the lever farther will cause less effort NOTE: ...and lets the valve blow up at a lower pressure What is the formula to find the volume of a sphere? 4/3π r³ What is the formula to find the area of a sphere? 4 π r² If two weights hang from two different strings attached to a bar, less pull is exerted by the weight of less weight. Which of the ff is true: a) the weight does not matter b) the length of the string does not matter c) the distance the weights have from the ground does not matter b) the length of the string does not matter The deeper you go with an inflated ball, the more difficult it is to hold it underwater. So the buoyancy a) will not change, no matter how deep you go into the water b) will increase, depending on how deep you go into the water c) will decrease, depending on how deep you go into the water b) will increase, depending on how deep you go into the water Rate of heat exchange is _____ through objects of greater temperature difference slower the same speed as faster faster Think about putting your thumb on the end of a hose makes the water spray. a) water flows faster through narrow areas that it does through wider b) the same amount of water will flow through the smaller and larger part of the hose at a given time c) all of the above c) all of the above This kind of engine consists of an intake, compression, combustion, and exhaust. 2 stroke 4 stroke 8 stroke 4 stroke What is the mechanical advantage of a wheel and axle? radius of axel to handle divided by the radius of the drum radius(axel to handle)/radius(drum) Statics and Equilibrium Formula for a moment? Force * distance ________ energy is stored in an object while _________ energy is energy in motion. Kinetic, Potential Potential, Kinetic Pressurized, Freeflow Potential, Kinetic I = Q/T Define I, Q, T Current, charge, time Voltage, momentum, time Voltage, charge, time Current, force, time Current, charge, time This device measures the current flow in a circuit Ammeter Voltmeter Multimeter Ammeter This device measures does the job of both measuring the flow in a current and the voltage Ammeter Voltmeter Multimeter Multimeter The formula for Power is Power = volts * amperes Units for a charge is coulomb, C ampere, A volts, V watts, W coulomb, C Units for current flow are coulomb, C ampere, A volts, V watts, W ampere, A Vise MA = (2*pi*length of handle) divided by what? pitch of thread Formula of Weight is Mass * Gravity Gravity is equal to 9.81 m/s² 32.3 ft/s² 22.1 mph 9.81 m/s² All the other answers are off by 0.1 only. 32.2 ft/s² 22 mph The formula for Density is Mass / Volume The formula for Relative Density is Density / Density(Reference Material) If you add salt into a liquid, the solution has a lower freezing point. This is because a) there is an increase in specific gravity b) there was a decrease of density in the reference material c) the volume of the saltwater solution decreased a) there is an increase in specific gravity Specific gravity usually means relative density with respect to water. The increase in the density of the liquid compared to regular water or gas makes salwater "more solid." Heat always distributes between objects travels from hot to cold travels from hot to cold Compressing air in a closed place will decrease the volume and raise the temperature a) True b) False, temperature will stay the same. c) False, volume will stay the same True A square plate is hanging by 4 wires (one on each corner). One breaks, and it's hanging by only 3 wires now. a) each wire now carry the same amount of weight b) the 2 diagonally across from each other hold an equal amount that is more than the lone wire in one corner c) the lone wire does not support. The 2 diagnoals carry the plate alone. b) the 2 diagonally across from each other hold an equal amount that is more than the lone wire in one corner Will an airplane with engine and propeller take off on a treadmill or converyor belt, regardless of the run setting? Will a glider (no engine or propeller) take off on a treadmill or converyor belt, regardless of the run setting? A common example of a first-class lever is a seesaw a wheelbarrow tongs a seesaw The force F required to balance the weight of 60 lbs on the lever, shown in the diagram above, is most nearly 210 lbs 240 lbs 672 lbs 210 lbs The mechanical advantage shown is 4 5 8 5 What effort must be exerted to the handles of the wheelbarrow shown carrying a load of 200 lbs (neglect the weight of the wheelbarrow in ur computation)? 40 lbs 50 lbs 65 lbs 50 lbs The bar, which is exactly 4 inches in length, has a 275 lbs weight on one end and a 125 lb weight on the opposite end. For the bar to balance, the distance from the 275 lb weight to the fulcrum point shd be (neglect the weight of the bar in ur computation) 1 1/4 inches 1 inch 3/4 inches 1 1/4 inches Neglecting friction, what is the mechanical advantage in using a single fixed pulley as shown ? 1 2 3 1 In the figure shown, the pulley system consists of a fixed block and a moveable block. Neglecting friction and the weight of the pulley system, what effort would be needed to lift a 100 lb weight 100 lbs 75 lbs 50 lbs 50 lbs The weight W is to be raised as shown in the figure by attaching the pull rope to the truck. If the weight is to be raised 8 ft, the truck will have to move 16 ft 24 ft 32 ft 24 ft The formula for an inclinded plane is MA = L/H MA = mechanical advantage L = length H = ? H = height MA = L / H L = length A gradual slope will provide a ________ mechanical advantage than a steep slope. higher lower higher In the figure shown, the service person is using a plank to roll a 300-pound barrel up to the bed of the truck. The force that must be applied is most nearly 200 pounds 150 pounds 100 pounds 100 pounds How do you find the mechanical advantage for a wheel and axel? Diameter/Radius In the figure shown, a bucket is being raised by a wheel-and-axel arrangement. If the distance from the center of the axle to the handle is 8 inches and the diameter of the drum around which the rope is wound is 4 inches, the theoretical mechanical advantage is 2 4 8 4 To make a 1/2" hole in a block of wood, use tool A B C B To cut a thread on a 1/2" brass rod, use tool A B C A The number 18 appearing on the tool shown above indicates depth of opening size of opening threads per inch threads per inch Which of the 1½ volt dry cell battery connections shown above will deliver 6 volts? 1 2 3 2 In the figure given, if the thickness of the wall of the pipe is ½", the inside diameter of the pipe is 3" 3 1/8" 3 1/4" 3" The figure above represents a revolving wheel. The numbers 1 and 2 indicate two fixed points on the wheel. The number 3 indicats the center of the wheel. Of the following, the most accurate statement is that a) point 1 makes more revolutins per minute than point 2 b) point 2 makes more revolutions per minute than point 1 c) points 1 and 2 make the same number of revolutions per minute c) points 1 and 2 make the same number of revolutions per minute In the figure shown, if gear A makes 14 revolutions, gear B will make 14 17 21 21 With the wheels in the position shown in the figure a) wheels S and T will rotate in opposite direction b) wheels S and T will rotate in the same directions c) wheels S and T will rotate at the same speed b) wheels S and T will rotate in the same directions In order to open the valve four times every second, the wheel must rotate at 12 rpm 18 rpm 24 rpm 24 rpm 4 times every second = 240 10 rods on the wheel 240/10 In the figure shown, a 160-lb individual jumps off an 800-lb raft to a point in the water 10 ft away. Theoretically, the raft will move a) 2 ft in the opposite direction b) 3 ft in the opposite direction c) 4 ft in the opposite direction a) 2 ft in the opposite direction The figure shows a lever-type safety valve. It will blow off at a lower pressure if weight W is increased moved to the left moved to the right moved to the left As shown in the figure, four air reservoirs have been filled with air by the air compressor. If the main line air gauge reads 100 lbs, then the tank air gauge will read 25 lbs 50 lbs 100 lbs 100 lbs In the figure above, the number of complete turns the vise handle must make to fully close the jaws is 14 16 18 20 18 In the figure shown, the center-to-center distance between the two poles is 1 3/4" 1 15/16" 1 7/8" 1 15/16" If an 8" level indicates 16 quarts of oil in the tank, then the number of quarts of oil to be added to raise the level from 6" to 8" is 2 quarts 4 quarts 6 quarts 4 quarts Which illustration depicts the compression stroke? X Y Z Z Both valves are closed and the piston is moving upwards What is the proper sequence of the four strokes of a piston in a gasoline engine W X Y Z X Z Y W Y Z X W Y Z X W The gauge shown above is a depth gauge feeler gauge thread gauge thread gauge The thread or screw-pitch gauge is used to determine the pitch and number of threads per inch of threaded fasteners. The wrench shown is generally used when a) a definite force must be applied to a nut or bolt head b) a tight nut must be broken loose c) rapid turning of the nut or bolt is of prime importance a definite force must be applied to a nut or bolt head The torque is read visually on a dial mounted on the handle of the wrench. It is used when a definte force must be applied. Which of the figures shown is the proper procedure for pulling adjustable wrenches? A B Both are proper procedures A The handle of the adjustable wrench should be pulled toward the side having the adjustable jaw. This will prevent the adjustable jaw from springing open and slipping off the nut. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. True False True Newton's Law describes a relationship between an object's _______ and _______ as the applied force. pressure, density weight, velocity mass, acceleration density, distance mass, acceleration In Newton's Third Law, force a) is neither created or destroyed b) if there is no opposing force, the motion will never stop. c) always elicits an equal, opposite force acting against it d) is the cause for intertia e) all of the above c) always elicits an equal, opposite force acting against it Whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction. A 150 lb man jumps off a 600 lb raft to a point in the water 12 ft away. Theoretially, the raft would move a) 12 ft in the opposite direction b) 9 ft in the opposite direction c) 6 ft in the opposite direction d) 3 ft in the opposite direction e) 1 ft in the opposite direction 3 ft in the opposite direction 150 lb x 12 ft = 600 lb x ? ft The mechanical advantage of a lever can be increased by a) placing the fulcrum closer to the object being lifted b) moving the effort force upwards the lever closer to the object being lifted c) lengthening the lever arm or by the placement of the fulcrum (base) d) both a and c e) all of the above d) both a and c A lever arm is in balance when the force x length of one side of a fulcrum is equal to the force x length on the other side of the fulcrum. With this info, test this concept: The force F needed to balance the lever is, in lbs, most nearly 10 lbs 14 lbs 15 lbs 18 lbs 10 lbs Then tension of a string in figure A is greater than the tension of a single spring in Figure B. The spring tension of springs supporting an object individually spreads the load between the individual springs. 10 lb weights are each suspended from a ceiling by 3 identical springs. In A, the extension of each spring is K) Nine times greater than in B L) Three times greater than in B M) The same as in B N) One-third less than in B O) One-ninth less than in B L) Three times greater than in B Pulleys. Which of the following is always not true about a pulley. a) a pulley system will reduce the force required to lift an object b) the mechanical advantage is proportional to the number of moveable and unmoveable pulleys in the system c) a moveable pulley provides less advantage as a fixed pulley d) both a and b e) all of the above e) all of the above What amount of force is required to move the weight (assume the supported objects all weight 100 lbs) in the pulley system? 50lbs What amount of force is required to move the weight (assume the supported objects all weight 100 lbs) in the pulley system? 33.3 lbs What amount of force is required to move the weight (assume the supported objects all weight 100 lbs) in the pulley system? 25 lbs The immoveable one pulley system provides ___ the force to lift the object and will have a ratio of 1:1 1/2 1 2 1/2 There is 1 rope. Divided evenly into 2, and no mechanical advantage, since the pulley is immoveable If the pulley is immoveable, what is the minimum force that must be applied to position 1 in order to raise the 20 lb weight at position 2 upwards 3 feet 20 lbs over 2 ft 10.1 lbs over 3 ft 7.5 lbs over 3 ft 10.1 lbs over 3 ft This is Boyles Law: a) Compressing a gas to 1/2 volume doubles the pressure b) If the pressure decreased by 1/2, the volume would double c) Both A and B d) None of the above c) Both A and B Actually, Boyle's law describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system. Charles' Law is when a) you heat some liquid, and the temperature changes, but the volume stays the same b) you open a can of coke, and the soda starts fizzing out c) both a and b d) none of the above b) you open a can of coke, and the soda starts fizzing out If gas is held at a constant pressure, the volume is directly proportional to the absolute temperature. Bernoulli's Principal is when a) a good pitcher throws a curve ball b) you siphon a gas tank c) when the pressure increases, the velocity increases d) both a and b e) both b and c d) all of the above d) both a and b Bernoulli's princiapl states that as the velocity of a fluid increases, its pressure decreases. The higher the altitude, the more dense the air. True False False The deeper an object is submerged, the more pressure is exerted upon it. True False True Which of the statements about weight are true? a) Weight is the same closer to the earth's surface as would be in midair b) Weight is greater on planets with greater mass c) Weight is consistent from location to location d) Both A and C e) All of the above f) None of the above b) Weight is greater on planets with greater mass Mass does not change and is not affected by gravity. Weight does, depending on the location. A and C would apply to Mass, but not weight. If Gear R is the driver, at the moment shown, Gear S is P) not moving Q) jammed R) moving at its highest speed S) moving in the same direction as Gear R T) moving in the opposite direction as Gear R T) moving in the opposite direction as Gear R If Gear A makes 14 revolutions, gear B will make A) 9 revolutions B) 14 revolutions C) 17 revolutions D) 21 revolutions E) 25 revoltions D) 21 revolutions _______ is the factor or ratio by which a mechanism multiplies the force or torque applied to it. Mechanical Advantage Output force Input force or distance w/c force is applied divided by distance over w/c a load is moved