Name______________________________________________Date___________________________________
Work and Simple Machines Quiz – 35 points
Term
Definition
1. Work
2. Power
3.Mechanical
Advantage
4. Efficiency
5. To qualify as a machine, a tool or device must do one or more of the following things:
a.
b.
c.
6. Explain what stops machines from being 100% efficient?
7. Why do motors and engines use oil and grease?
For the following examples write YES on the line if work is being done and NO on the line if work is not being
done.
8. ________A teacher applies a force to a wall and becomes exhausted.
9. ________A book falls off a table and free falls to the ground.
10. ________A waiter carries a tray full of meals above his head by one arm straight across the room at constant speed.
Is work being done on the tray?
11. ________A rocket accelerates through space.
12. ________You carry a bag up the stairs. Is work being done on the bag?
13. ________Tasha pushes her little sister on the swing. Is work being done on the little sister?
Multiple Choice. Choose the best answer and write it on the line.
14. ________Who does more work - a man who lifts a large box from the ground up into the back of a truck, or a man
who puts the same box on a trolley and wheels it up a ramp into the truck?
A. the man who lifts it
B. the man with the trolley
C. they do the same work
15. _______How many ways are there to calculate mechanical advantage for a lever?
A. 400 newtons
B. 100 joules
C. 400 joules
16. _______A machine is efficient when
A.
B.
C.
D.
E.
It transfers most of its effort work into resistance work
It transfers most of its resistance work into effort work
It transfers most of its resistance force into effort force
All of the above
None of the above
17..________Machines can NOT change which of the following?
A.
B.
C.
D.
E.
Resistance force
Work
Distance
Direction
Effort force
18. ________Marcos pushes down on a lever with 10 N of force and the lever exerts a resistance force of 15N. The
machine has:
A. No mechanical advantage
B. A mechanical advantage
C. Low efficiency
D. High efficiency
For the following situations write YES if the machine will give you a mechanical advantage and NO if the machine will
not give you a mechanical advantage.
19. _________You have to lift a box 2.5 meters off the ground so you make an 1.5 meter inclined plane to help you.
20. _________You are using a lever to help lift something heavy so you position the fulcrum exactly in the middle of the
lever (meaning the effort arm and resistance arm have an equal distance)
21. _________To lift another heavy box you design a pulley system that uses 3 pulleys supporting 3 sections of rope.
22. ________You have a mass of 50 kg and you need to walk up 2 flights of stairs. There is a ramp next to the stairs that
is twice as long (distance) as the stairs but you take it anyway.
Word problems. Solve the problems and SHOW ALL WORK (or else no credit).
23. Ben Travlun carries a 200-N suitcase up three flights of stairs (a height of 10.0 m) and then pushes it with a horizontal
force of 50.0 N at a constant speed for a horizontal distance of 35.0 meters. How much work does Ben do on his suitcase
during this entire motion?
24. How much work is done by an applied force to lift a 15-Newton block 3.0 meters vertically at a constant speed?
25. a. A student with a mass of 80.0 kg runs up three flights of stairs in 12.0 sec. The student has gone a vertical distance
of 8.0 m. Determine the amount of work done by the student to elevate his body to this height. B. What is the power
produced from the student above? (this is a 2 part question!)
Extra Credit: 5 points.
A tired squirrel (mass of 1 kg) does push-ups by applying a force to elevate its center-of-mass by 5 cm. Estimate the
number of push-ups that a tired squirrel must do in order to do a approximately 5.0 Joules of work.