1.
Which of the following is a calculation of work?
Correct Answer
E. Both 'A' and 'D' are correct.
Explanation
Answer A will provide work while not going against gravity, say sliding a book on a table.
Answer B will provide work while going against gravity, like sliding a book up a ramp.
2.
In the image above, what hand does more work.
Correct Answer
C. C
Explanation
Force C will do the most work because it is entirely in the direction of the motion.
3.
Alexander has a mass of 70 kilograms. HIs apartment is on the second floor, 5 meters up from ground level. How much work does he do against gravity each time e clims the stairs to his apartment?
Correct Answer
D. 686N
Explanation
W=FD
W=70kg x 9.8m/s/s
W=686N
4.
Power is measure in _______, because the man who invented the steam engine was named ______ _____. Power (P) is equal to ______ ______ by ______.
Correct Answer
E. Watts; James Watts; work; divided; time
Explanation
Answer E is the only choice that correctly fills in all of the blanks.
Choice D is wrong because of the measurement of power and because of the name of the inventor.
5.
What is a device with moving parts that work together to accomplish a task?
Correct Answer
C. Machine
Explanation
Answer C is the only option that applies here. Answers A, B, D, and E are all example of C.
6.
In a machine, the ______ ______ in newtons, or the force that the machine applies to what you are trying to move, divided by the _____ _____ in newtons, or the force you apply to the machine, is known as the ______ ______ of the machine.
Correct Answer
E. Output force; input force; mechanical advantage
Explanation
Answers A & B are incorrect because of the order of forces (both list input then output, but the question calls for output then input). All choices that list work done or power used are incorrect because of these words. This leaves choice C as the only correct answer.
NOTE THAT THIS DOES NOT APPLY TO LEVERS OR GEARS OR RAMPS
7.
The _____ _____ of a machine can never be _____ than the ______ ______. When you design a machine that multiplies force, you pay by having to apply the force over a ______ distance.
Correct Answer
distance, greater, input, output, work, work, force, force, initial, final, greater
Explanation
The output work of a machine can never be greater than the input work. When you design a machine that multiplies force, you pay by having to apply the force over a greater distance.
Nature does not give something for nothing. You cannot get more than what you have.
8.
How do you find the mechanical advantage of a lever? Remember to include units in your answer.
9.
Describe the three classes of levers. Include the location of the fulcrum and the amount of force that is input and output for each class.
10.
The force in a rope is called the ____.
Correct Answer
mechanical advantage, output work, force, tension, height, teeth
Explanation
The answer is tension.
11.
How do you fid the gear ratio?
12.
How do you find the mechanical advantage of a ramp?
13.
How do you find the mechanical advantage of a screw?
14.
When we measure how close to perfect a machine is, we are measuring its _____.
Correct Answer
length, complexity, friction, mechanical advantage, electricity, efficiency, type, class, joule
Explanation
Efficiency is how close to perfect a machine is.
15.
Efficiency is measured in percentages. Why is no machine 100% efficient? Copy the text below (including the dashes), paste it into your answer and then use one word.Some energy is lost to ________ in all machines.--
16.
Any process that is not 100% efficient is ___________
Correct Answer
impossible, irreversible, reversible
Explanation
Because some energy cannot get back into potential or kinetic energy, any process with less than 100% efficiency is irreversible.
17.
The efficiency is less than 100% for virtually all process that do what?
18.
A simple machine has a mechanical advantage of 5. If the output force is 10N, what is the input force?