Physical Science Final Exam 8th Grade Chapter 8, 9, And Part Of 10
Chapter: 8, 9, 10, 11, 12
Questions and Answers
- 1.
In which situation is a person doing work on an object? (CHAPTER 8)
- A.
A worker holds a box 1 m off the floor
- B.
A student walks 1 m/s while wearing a backpack that weighs 15 N
- C.
A school crossing guard raises a stop sign that weighs 10 N.
- D.
A man exerts a 350 N force on a rope attached to a house
Correct Answer
C. A school crossing guard raises a stop sign that weighs 10 N.Explanation
A person is doing work on an object when they exert a force on the object and the object moves in the same direction as the force applied. In this situation, the school crossing guard is raising a stop sign that weighs 10 N. By exerting a force on the stop sign and lifting it, the guard is doing work on the object. The other scenarios mentioned do not involve the object moving in the same direction as the force applied, so work is not being done on the object in those situations.Rate this question:
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- 2.
Which of the following increase the mechanical advantage of a first-class lever? (CHAPTER 8)
- A.
Applying a greater input force
- B.
Decreasing the load
- C.
Increasing the rate at which force is applied
- D.
Moving the fulcrum closer to the load
Correct Answer
D. Moving the fulcrum closer to the loadExplanation
Moving the fulcrum closer to the load increases the mechanical advantage of a first-class lever. This is because the mechanical advantage of a lever is determined by the ratio of the distances from the fulcrum to the input force and the fulcrum to the load. By moving the fulcrum closer to the load, the distance from the fulcrum to the load decreases, while the distance from the fulcrum to the input force remains the same. As a result, the mechanical advantage increases, making it easier to lift the load with less input force.Rate this question:
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- 3.
The unit for work is ________. (CHAPTER 8)
- A.
Newton
- B.
Joule
- C.
Watt
- D.
Joule per second
Correct Answer
B. JouleExplanation
The unit for work is Joule. Work is defined as the amount of energy transferred by a force acting through a distance. Joule is the SI unit for energy and work, and it is equal to the work done when a force of one newton is applied over a distance of one meter. Therefore, the correct unit for work is Joule.Rate this question:
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- 4.
You apply 200 N to a machine and the machine applies 2,000 N to an object. what is the mechanical advantage? (CHAPTER 8)
- A.
10
- B.
0
- C.
20
Correct Answer
A. 10Explanation
The mechanical advantage is calculated by dividing the output force (2,000 N) by the input force (200 N). In this case, 2,000 N divided by 200 N gives a mechanical advantage of 10. This means that the machine amplifies the input force by a factor of 10, allowing the user to exert a greater force on the object.Rate this question:
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- 5.
Input force _________. (CHAPTER 8)
- A.
Changes in size when done by machine
- B.
Changes in direction when done by machine
- C.
Changes in size and direction when done by machine
Correct Answer
C. Changes in size and direction when done by machineExplanation
When a machine is used to perform a task, it can cause changes in both the size and the direction of the input force. This means that the force applied to the machine can result in both a change in the size or magnitude of the force, as well as a change in the direction in which the force is applied. Therefore, the correct answer is "Changes in size and direction when done by machine."Rate this question:
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- 6.
Which of the following could be a machine's mechanical efficiency? (CHAPTER 8)
- A.
10%
- B.
25%
- C.
95%
Correct Answer
C. 95%Explanation
A machine's mechanical efficiency refers to the ratio of output work to input work, expressed as a percentage. A mechanical efficiency of 95% suggests that the machine is able to convert 95% of the input work into useful output work, with only a small percentage being lost as waste or friction. This indicates a highly efficient machine that is able to perform its intended task with minimal energy loss.Rate this question:
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- 7.
A _______ is the SI unit equivalent to 1 newton meter. (CHAPTER 8)
- A.
Newton
- B.
Joule
- C.
Watt
- D.
Meter
Correct Answer
B. JouleExplanation
A joule is the SI unit equivalent to 1 newton meter. It is a unit of energy, work, or heat. It is derived from the combination of the SI unit for force (newton) and the SI unit for distance (meter). Therefore, when a force of 1 newton is applied to an object and it moves a distance of 1 meter in the direction of the force, the work done is equal to 1 joule.Rate this question:
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- 8.
In a basketball game, what is NOT considered to be work done on an object. (CHAPTER 8)
- A.
Running down the court without a ball
- B.
Throwing the ball to a teammate
- C.
Dribbling the ball in place
- D.
Slam-dunking the ball
Correct Answer
A. Running down the court without a ballExplanation
Running down the court without a ball is not considered work done on an object because work is defined as the transfer of energy to an object by the application of a force that causes the object to move in the direction of the force. In this case, running down the court without a ball does not involve any force being applied to an object to cause it to move, so no work is being done.Rate this question:
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- 9.
When a machine increases the size of the force exerted, the distance through which the force is exerted _____ (CHAPTER 8)
- A.
Must increase
- B.
Must decrease
- C.
Must stay the same
- D.
Must double
Correct Answer
B. Must decreaseExplanation
When a machine increases the size of the force exerted, the distance through which the force is exerted must decrease. This is because of the principle of work, which states that work is equal to force multiplied by distance. As the force exerted increases, the machine can achieve the same amount of work by decreasing the distance through which the force is exerted. This allows the machine to exert a greater force over a shorter distance, resulting in increased efficiency. Therefore, the distance must decrease in order to maintain the same amount of work.Rate this question:
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- 10.
A ______ is a bar that pivots on a fulcrum. (CHAPTER 8)
- A.
Wedge
- B.
Pulley
- C.
Screw
- D.
Lever
Correct Answer
D. LeverExplanation
A lever is a bar that pivots on a fulcrum, allowing for the amplification of force or the movement of objects. It consists of three main components: the fulcrum, the load, and the effort. By applying force at one end of the lever, the load at the other end can be moved or lifted. Levers are commonly used in various applications, such as seesaws, crowbars, and even human limbs. They are essential tools in mechanics and engineering, providing mechanical advantage and facilitating work.Rate this question:
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- 11.
Because of friction, the _________ of a machine is always less than 100% (CHAPTER 8)
- A.
Mechanical advantage
- B.
Mechanical Efficiency
- C.
Work output
- D.
Work input
Correct Answer
B. Mechanical EfficiencyExplanation
Mechanical efficiency refers to the ratio of the machine's work output to its work input, taking into account the losses due to friction. Friction always causes some energy to be converted into heat, resulting in a decrease in the overall efficiency of the machine. Therefore, the mechanical efficiency of a machine is always less than 100%.Rate this question:
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- 12.
A ______ is a device that changes in size or directions of the force exerted on an object. (CHAPTER 8)
- A.
Machine
- B.
Machine
- C.
Machine
Correct Answer
A. MachineExplanation
A machine is a device that can change the size or direction of the force exerted on an object. Machines are designed to make work easier by using mechanical advantage to multiply force or change its direction. They can be simple machines like levers and pulleys, or complex machines like engines and turbines. By utilizing various mechanisms, machines can alter the forces applied to objects, allowing for tasks to be accomplished more efficiently.Rate this question:
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- 13.
A machine's __________ indicates how many times the machine multiplies force by comparing the input force with the output force. (CHAPTER 8)
- A.
Not this one
- B.
Still not this one
- C.
Defiantly this one: Mechanical Advantage
Correct Answer
C. Defiantly this one: Mechanical AdvantageExplanation
The term "Mechanical Advantage" refers to a machine's ability to multiply force. It is a measure of how much the machine can increase the input force to produce a greater output force. By comparing the input force with the output force, the mechanical advantage of a machine can be determined. Therefore, the given answer, "Mechanical Advantage," correctly explains the concept of how a machine multiplies force.Rate this question:
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- 14.
When a machine changes the size of a force, the ______ must also change (CHAPTER 8)
- A.
Shape
- B.
Height
- C.
Distance
Correct Answer
C. DistanceExplanation
When a machine changes the size of a force, the distance must also change. This is because machines work by trading off force for distance. In simple terms, if a machine increases the force applied, the distance over which the force is applied will decrease. Conversely, if a machine decreases the force applied, the distance over which the force is applied will increase. This principle is known as the principle of mechanical advantage and is a fundamental concept in understanding how machines work.Rate this question:
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- 15.
A block and tackle is an example of a _______ (CHAPTER 8)
- A.
Lever
- B.
Compound machine
- C.
Ideal Machine
- D.
Wheel and Axle
Correct Answer
B. Compound machineExplanation
A block and tackle is an example of a compound machine because it consists of multiple simple machines working together to achieve a mechanical advantage. In this case, the block and tackle system utilizes both the wheel and axle and the lever principles to make lifting heavy objects easier. The wheel and axle allows for the rotation of the pulleys, while the lever principle allows for the distribution of force across multiple ropes and pulleys, resulting in a greater mechanical advantage.Rate this question:
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- 16.
The work you do on a machine, such as a turning a screwdriver, is called ________ (CHAPTER 8)
- A.
Work Input
- B.
Work Output
- C.
Mechanical Effeciency
- D.
Mechanical Advantage
Correct Answer
A. Work InputExplanation
Work input refers to the amount of work that is put into a machine or system. It is the work done on the machine or the energy transferred to the machine in order to perform a task. In the given question, the work done on a machine, such as turning a screwdriver, is referred to as work input.Rate this question:
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- 17.
Juan and Anita each lift an identical stack of books the same distance onto a table, but Anita does the job twice as fast. Therefore her actions involve twice as much _____ (CHAPTER 8)
- A.
Power
- B.
Work input
- C.
Work output
- D.
Efficiency
Correct Answer
A. PowerExplanation
Anita completes the job twice as fast as Juan, which means she does the same amount of work in half the time. Power is the measure of how quickly work is done, so Anita's actions involve twice as much power compared to Juan.Rate this question:
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- 18.
_____ is done on an object when a force exerted on the object causes it to move in the direction of the force. (CHAPTER 8)
- A.
Joule
- B.
Watt
- C.
Work
- D.
Power
Correct Answer
C. WorkExplanation
Work is done on an object when a force exerted on the object causes it to move in the direction of the force. Work is a measure of the energy transferred to or from an object by means of a force acting on the object. It is calculated by multiplying the magnitude of the force applied to an object by the distance the object moves in the direction of the force.Rate this question:
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- 19.
Which of the following light bulbs does the most work each second? (CHAPTER 8)
- A.
100 watt bulb
- B.
60 watt bulb
- C.
40 watt bulb
- D.
All bulbs do the same amount of work each second
Correct Answer
A. 100 watt bulbExplanation
The 100 watt bulb does the most work each second because wattage is a measure of power, which is the rate at which work is done. Therefore, the higher the wattage, the more work is done per second.Rate this question:
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- 20.
What does a fixed pulley change? (CHAPTER 8)
- A.
Neither the direction nor the size of a force
- B.
Both the size and direction of a force
- C.
The direction of a force
- D.
The size of a force
Correct Answer
C. The direction of a forceExplanation
A fixed pulley does not change the size of a force because the effort force required to lift an object is the same as the weight of the object. However, it does change the direction of the force. When using a fixed pulley, the force applied downwards to lift the object is redirected upwards, making it easier to lift heavy objects by pulling downwards instead of lifting upwards. Therefore, the correct answer is that a fixed pulley changes the direction of a force.Rate this question:
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- 21.
Levers are divided into classes according to the location of ________ (CHAPTER 8)
- A.
The Input force
- B.
The Fulcrum
- C.
The Fulcrum, the load, and the input force
- D.
The load
Correct Answer
C. The Fulcrum, the load, and the input forceExplanation
Levers are divided into classes according to the location of the fulcrum, the load, and the input force. This means that the position of these three elements determines the class of the lever.Rate this question:
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- 22.
Work is being done when ________ (CHAPTER 8)
- A.
An object is moving after you apply a force to it
- B.
You exert a force that moves an object in the direction of the force
- C.
You do something that is difficult
- D.
You apply a force to an object
Correct Answer
B. You exert a force that moves an object in the direction of the forceExplanation
When you exert a force on an object and it moves in the direction of the force, work is being done. This is because work is defined as the transfer of energy that occurs when a force is applied to an object and it moves in the direction of the force. In this scenario, the force applied by you causes the object to move, which means that work is being done on the object.Rate this question:
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- 23.
A _______ is a simple machine consisting of a grooved wheel that holds a rope or a cable (CHAPTER 8)
- A.
Wheel and axle
- B.
Pulley
- C.
Wedge
Correct Answer
B. PulleyExplanation
A pulley is a simple machine that consists of a grooved wheel that holds a rope or a cable. It is used to lift or move heavy objects by changing the direction or magnitude of the force applied. By wrapping the rope around the wheel and axle of the pulley, it allows for easier lifting and pulling of objects. This makes the pulley an efficient tool for tasks that require mechanical advantage.Rate this question:
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- 24.
A _______ is a simple machine consisting of two circular objects of different sizes (CHAPTER 8)
- A.
Wedge
- B.
Wheel and axle
- C.
Pulley
Correct Answer
B. Wheel and axleExplanation
A wheel and axle is a simple machine consisting of two circular objects of different sizes. The larger circular object is called the wheel, while the smaller circular object is called the axle. The axle is attached to the center of the wheel and allows it to rotate. This simple machine is commonly used in various applications, such as vehicles, bicycles, and door knobs, to transfer and amplify rotational motion.Rate this question:
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- 25.
A ______ is a double inclined plane that moves (CHAPTER 8)
- A.
Wheel and axle
- B.
Pulley
- C.
Wedge
Correct Answer
C. WedgeExplanation
A wedge is a double inclined plane that moves. It is a simple machine with a triangular shape that is used to separate or lift objects by applying force to its thick end. When the wedge is pushed or driven into a material, it creates a split or separation due to its shape and the applied force. This makes it an effective tool for tasks such as splitting wood, cutting through materials, or holding objects in place.Rate this question:
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- 26.
Which of the following machines always has a mechanical advantage of less than 1? (CHAPTER 8)
- A.
A poorly lubricated, movable pulley
- B.
A long, thin wedge
- C.
Third-class lever
- D.
Wheel and axle
Correct Answer
C. Third-class leverExplanation
A third-class lever always has a mechanical advantage of less than 1 because the effort arm is shorter than the load arm. In a third-class lever, the effort is applied closer to the fulcrum than the load, resulting in a smaller force being exerted on the load compared to the effort applied. This means that the force output is always less than the force input, resulting in a mechanical advantage of less than 1.Rate this question:
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- 27.
Which of the following statements about inclined planes is NOT true? (CHAPTER 8)
- A.
An example of an inclined plane is a wedge
- B.
Inclined planes allow you to apply a smaller force over a smaller distance
- C.
Egyptian used inclined planes to build the Great Pyramid
- D.
A screw is a type of inclined plane.
Correct Answer
B. Inclined planes allow you to apply a smaller force over a smaller distanceExplanation
Inclined planes do not allow you to apply a smaller force over a smaller distance. In fact, inclined planes allow you to apply a smaller force over a longer distance, making it easier to move objects vertically or horizontally. This is because the inclined plane increases the distance over which the force is applied, reducing the amount of force needed to move the object.Rate this question:
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- 28.
The work output for a machine is always less than the work input because (CHAPTER 8)
- A.
Power is the rate at which work is done
- B.
Some of the work done is used to overcome distance
- C.
Some of the work done is used to overcome friction
- D.
All machines have a mechanical advantage
Correct Answer
C. Some of the work done is used to overcome frictionExplanation
The work output for a machine is always less than the work input because some of the work done is used to overcome friction. Friction is a force that opposes motion and is present in all machines. When a machine is used, some of the work input is used to overcome this frictional force, resulting in a decrease in the work output. Therefore, the work output is always less than the work input in a machine.Rate this question:
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- 29.
If you do 50 J of work in 5 s, your power is (CHAPTER 8)
- A.
45 W
- B.
55 W
- C.
250 W
- D.
10 W
Correct Answer
D. 10 WExplanation
The power is calculated by dividing the work done by the time taken. In this case, the work done is 50 J and the time taken is 5 s. Therefore, the power is 10 W.Rate this question:
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- 30.
A ______ is also expressed as joule per second (CHAPTER 8)
- A.
Power
- B.
Work
- C.
Watt
- D.
Joule
Correct Answer
C. WattExplanation
The correct answer is Watt. Power is a measure of how quickly work is done or energy is transferred. It is expressed in units of joules per second, which is also known as a watt.Rate this question:
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- 31.
Suppose you have just lifted a 50 N bowling ball 2 M above the floor. Which of the following is true? (CHAPTER 9)
- A.
The ball's gravitational potential energy is equal to 50 J
- B.
The ball's kinetic energy is equal to 400 J
- C.
Your body is exerting a force of 100 N on the ball
- D.
You performed work equal to 100 J to lift the ball
Correct Answer
D. You performed work equal to 100 J to lift the ballExplanation
When an object is lifted against gravity, work is done on the object. The work done is equal to the force applied multiplied by the distance over which the force is applied. In this case, the force applied is equal to the weight of the ball, which is 50 N, and the distance over which the force is applied is 2 M. Therefore, the work done to lift the ball is equal to 50 N * 2 M = 100 J.Rate this question:
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- 32.
During photosynthesis, plants (CHAPTER 9)
- A.
Combine carbon dioxide with oxygen
- B.
Convert thermal energy into kinetic energy
- C.
Break down food molecules to release energy
- D.
Use light energy to produce new substances with chemical energy
Correct Answer
D. Use light energy to produce new substances with chemical energyExplanation
Plants use light energy during photosynthesis to produce new substances with chemical energy. Photosynthesis is the process by which plants convert light energy into chemical energy in the form of glucose. This chemical energy is stored in the plant and can be used for various metabolic processes. Therefore, the correct answer is "use light energy to produce new substances with chemical energy."Rate this question:
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- 33.
The _______ in the sugars and starches of food fuels all your body functions and movements, and provides the thermal energy that keeps your body temperature constant (CHAPTER 9)
- A.
Electrical energy
- B.
Light energy
- C.
Nuclear energy
- D.
Chemical energy
Correct Answer
D. Chemical energyExplanation
Chemical energy is the correct answer because sugars and starches in food are broken down during digestion into smaller molecules, releasing energy in the process. This energy is then used by the body to carry out various functions and movements. Additionally, the energy released from the breakdown of these molecules helps to maintain the body's temperature. Therefore, chemical energy is the form of energy that fuels all body functions and movements and helps regulate body temperature.Rate this question:
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- 34.
Coal burning power plants use steam driven turbines to generate electrical energy. This is an example of _____ (CHAPTER 9)
- A.
Energy conversion
- B.
Both of the answers
- C.
Friction force
Correct Answer
A. Energy conversionExplanation
The given answer "energy conversion" is correct because coal burning power plants convert the chemical energy stored in coal into thermal energy through combustion. This thermal energy is then used to heat water and produce steam, which drives the turbines to generate electrical energy. Therefore, the process involves the conversion of one form of energy (chemical) into another form (thermal and then electrical).Rate this question:
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- 35.
Nonindustrialized countries rely heavily on _____ for energy (CHAPTER 9)
- A.
Biomass
- B.
Natural gas
- C.
Sun
Correct Answer
A. BiomassExplanation
Nonindustrialized countries rely heavily on biomass for energy. Biomass refers to organic matter, such as wood, crop residues, and animal waste, that can be used as a fuel source. These countries often lack access to modern energy infrastructure and rely on traditional methods of energy production. Biomass is readily available and can be easily obtained and used for cooking, heating, and other energy needs. It is a sustainable and renewable energy source that is abundant in nonindustrialized countries, making it a viable option for meeting their energy demands.Rate this question:
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- 36.
The cleanest burning fossil fuel (CHAPTER 9)
- A.
Nuclear energy
- B.
Steam
- C.
Geothermal
- D.
Natural gas
Correct Answer
D. Natural gasExplanation
Natural gas is considered the cleanest burning fossil fuel because it produces fewer emissions compared to other fossil fuels like coal and oil. When natural gas is burned, it releases lower levels of carbon dioxide, sulfur dioxide, and nitrogen oxide, which are major contributors to air pollution and climate change. Additionally, natural gas combustion produces minimal ash and particulate matter. This makes natural gas a more environmentally friendly option for generating electricity and heating compared to other fossil fuels.Rate this question:
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- 37.
Our most important energy resource is (CHAPTER 9)
- A.
Nuclear energy
- B.
Sun
- C.
Steam
- D.
Fossil fuel
Correct Answer
B. SunExplanation
The sun is our most important energy resource because it provides the Earth with heat and light energy through nuclear fusion. Solar energy is renewable and abundant, making it a sustainable source of power. It is harnessed through various technologies such as solar panels and solar thermal systems to generate electricity and heat water. Additionally, the sun's energy is also responsible for driving weather patterns, photosynthesis in plants, and the water cycle, making it crucial for sustaining life on Earth.Rate this question:
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- 38.
Which of the following is NOT a renewable resource? (CHAPTER 9)
- A.
Nuclear energy
- B.
Natural gas
- C.
Sun
- D.
Fossil fuel
Correct Answer
A. Nuclear energyExplanation
Nuclear energy is not a renewable resource because it is generated from the process of nuclear fission, which involves splitting atoms to release energy. This process requires uranium or plutonium, which are finite resources and cannot be replenished naturally. In contrast, renewable resources like the sun, natural gas, and even fossil fuels can be replenished over time through natural processes.Rate this question:
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- 39.
Fossil-fuel and nuclear plants use _____ to turn a turbine that rotates the generator (CHAPTER 9)
- A.
Sun
- B.
Steam
- C.
Geothermal energy
Correct Answer
B. SteamExplanation
Fossil-fuel and nuclear plants use steam to turn a turbine that rotates the generator. In these types of power plants, heat is generated by burning fossil fuels or through a nuclear reaction. This heat is then used to produce steam, which is directed towards the turbine. The high-pressure steam causes the turbine to spin, and as a result, the generator connected to the turbine also rotates, producing electricity. Therefore, steam plays a crucial role in the generation of electricity in fossil-fuel and nuclear plants.Rate this question:
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- 40.
The energy source powering the geyser Old Faithful in Yellowstone National Park is (CHAPTER 9)
- A.
Geothermal
- B.
Steam
- C.
Water
- D.
Fossil fuel
Correct Answer
A. GeothermalExplanation
The correct answer is geothermal because geysers, including Old Faithful, are powered by geothermal energy. Geothermal energy is generated by heat from the Earth's core, which heats up water and creates steam. This steam builds up pressure underground and eventually erupts through the surface, causing the geyser to erupt. Therefore, geothermal energy is the energy source that powers Old Faithful.Rate this question:
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- 41.
Our most important nonrenewable resource is (CHAPTER 9)
- A.
Fossil fuel
- B.
Sun
- C.
Oil
Correct Answer
A. Fossil fuelExplanation
Fossil fuel is the correct answer because it is the most important nonrenewable resource. Fossil fuels, such as coal, oil, and natural gas, are formed from the remains of plants and animals that lived millions of years ago. These fuels are burned to produce energy and are widely used for electricity generation, transportation, and heating. However, fossil fuels are finite resources that take millions of years to form, making them nonrenewable. As a result, the over-reliance on fossil fuels has led to concerns about their depletion and the environmental impact of their combustion, including air pollution and climate change.Rate this question:
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- 42.
Which type of energy is NOT correctly described? (CHAPTER 9)
- A.
Sound energy: energy that can travel through a vacuum
- B.
Light energy: the result of vibrations of electrically charged particles
- C.
Electrical energy: the energy of moving electrons
- D.
Thermal energy: a measure of particle motion
Correct Answer
A. Sound energy: energy that can travel through a vacuumExplanation
Sound energy is a form of energy that requires a medium such as air, water, or solids to travel through. It cannot travel through a vacuum because a vacuum is an empty space devoid of any particles for sound waves to propagate. Therefore, the given description of sound energy is incorrect.Rate this question:
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- 43.
_____ is a force that opposes the motion between two surfaces that are touching (CHAPTER 9)
- A.
Mass
- B.
Friction
- C.
Condensation
Correct Answer
B. FrictionExplanation
Friction is a force that opposes the motion between two surfaces that are touching. When two objects are in contact and one tries to slide or move over the other, friction comes into play. It acts in the opposite direction to the motion and makes it difficult for the objects to move smoothly. Friction arises due to the roughness of the surfaces and the interlocking of their irregularities. It is an essential force in our daily lives, as it allows us to walk, drive, and hold objects without slipping.Rate this question:
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- 44.
What is involved in a closed system such as a roller coast (CHAPTER 9)
- A.
The cars
- B.
The track
- C.
The air
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
In a closed system such as a roller coaster, all of the mentioned elements are involved. The cars, track, and air are all part of the system and interact with each other. The cars move along the track, which provides the structure and path for the roller coaster. The air also plays a role in the ride, affecting the speed and dynamics of the coaster. Therefore, all of the above options are involved in a closed system like a roller coaster.Rate this question:
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- 45.
The __________ states that energy can be neither created nor destroyed (CHAPTER 9)
- A.
Law of conservation of energy
- B.
Periodic law
- C.
The kinetic law
Correct Answer
A. Law of conservation of energyExplanation
The law of conservation of energy states that energy cannot be created or destroyed, but it can only be transferred or transformed from one form to another. This principle is based on the understanding that energy is a fundamental quantity in the universe and is always conserved in any physical process. It is a fundamental law in physics and has wide-ranging applications in various fields, including mechanics, thermodynamics, and electromagnetism.Rate this question:
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- 46.
How does a light bulb conserve energy? (CHAPTER 9)
- A.
Some energy is converted into thermal energy
- B.
Some energy is converted into light energy
- C.
Both a and b
Correct Answer
C. Both a and bExplanation
A light bulb conserves energy by converting some of the electrical energy it receives into both thermal energy and light energy. This means that it does not waste all of the energy it consumes, but instead utilizes it to produce both heat and light. By converting the electrical energy into useful forms, the light bulb is able to be more energy-efficient and conserve energy.Rate this question:
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- 47.
Which of the following is NOT an energy resource? (CHAPTER 9)
- A.
The heat inside the Earth
- B.
Plant matter
- C.
Falling water
- D.
Electric generator
Correct Answer
D. Electric generatorExplanation
An electric generator is not an energy resource because it is a device that converts mechanical energy into electrical energy. It does not produce energy itself, but rather transforms energy from another source, such as fossil fuels or renewable sources like wind or water, into electricity. On the other hand, the heat inside the Earth, plant matter, and falling water are all examples of energy resources as they can be harnessed directly to generate power.Rate this question:
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- 48.
When one object does work on another, energy is ______ (CHAPTER 9)
- A.
Transferred
- B.
Destroyed
- C.
None of the answers
- D.
Created
Correct Answer
A. TransferredExplanation
When one object does work on another, energy is transferred. This is because work is defined as the transfer of energy from one object to another. When an object exerts a force on another object and causes it to move, energy is transferred from the first object to the second object. This transfer of energy allows the second object to gain energy and perform work. Therefore, the correct answer is "transferred."Rate this question:
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- 49.
More effcient light bulbs produce more _____ (CHAPTER 9)
- A.
Electrical
- B.
Light energy
- C.
Thermal energy
- D.
Waste
Correct Answer
B. Light energyExplanation
More efficient light bulbs produce more light energy because they convert a higher percentage of the electrical energy they receive into visible light. This means that less energy is wasted as heat, resulting in a higher output of light energy.Rate this question:
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- 50.
The thermal energy of a substance changes with the ________ of its particles. (CHAPTER 9)
- A.
Solar energy
- B.
None of the answers
- C.
Gravitational potential energy
- D.
Kinetic energy
Correct Answer
D. Kinetic energyExplanation
The thermal energy of a substance changes with the kinetic energy of its particles. This is because thermal energy is the total energy of all the particles in a substance, and kinetic energy is the energy associated with the motion of particles. As the particles move faster, their kinetic energy increases, leading to an increase in the thermal energy of the substance. Therefore, the correct answer is kinetic energy.Rate this question:
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