Question

Skills in the Skills and Reference Handbook at the end of your textbook.
Machine Increases or Decreases Increases or Decreases
Input Force Input Distance
Tire jack Decreases Increases
Lug wrench
Rowing oar
Summary: As input force decreases, the input distance increases.
Machines Do Work (pages 417–418)
1. Is the following sentence true or false? A machine can make work easier
to do by changing the size of the force needed, the direction of a force, or
the distance over which a force acts.
2. Consider the equation Work � Force � Distance. If a machine increases
the distance over which a force is exerted, the force required to do a
given amount of work .
3. You make several trips to unload a few heavy items from a car instead
of moving them all at once. Does the total distance over which you exert
yourself increase or decrease?
Work Input and Work Output (pages 419–420)
4. The work done by a machine is always less than the work done on a
machine because of . Circle the correct answer.
attraction friction gravity
Physical Science Reading and Study Workbook Level B ■ Chapter 14 163
© by Savvas Learning Company LLC. publishing as Savvas Prentice Hall. All rights reserved.



5. Circle the letter of the definition for input force.
a. the amount of force exerted by a machine
b. the amount of work done by a machine
c. the amount of force exerted on a machine
6. Is the following sentence true or false? Every machine uses some of its
work input to overcome friction.
7. Circle the letter of the expression that equals the work output
of a machine.
a.
b. Output distance � Input distance
c. Output distance � Output force
8. Is the following sentence true or false? Output work always is less than
input work.
For questions 9 through 11, refer to the figure below.
9. Which arrow represents the input force? Label it on the figure.
10. Which arrow represents the input distance? Label it on the figure.
11. Which arrow represents the output force? Label it on the figure.

Answer 1

Here are the answers:

1. True.

2. Decreases.

3. Increases (you travel more total distance when you make several trips).

4. friction.

5. c. the amount of force exerted on a machine.

6. True.

7. c. Output distance × Output force.

8. True.

9–11. I can’t see the figure. To label it yourself:
- Input force: mark the arrow where you (or the user) push or pull on the machine.
- Input distance: mark the arrow showing how far that point on the machine moves (the distance the input force travels).
- Output force: mark the arrow showing the force the machine exerts on the load/object.

If you upload or describe the figure and the arrow labels (for example, A, B, C and their directions/positions), I’ll label which is input force, input distance, and output force.