CHAPTER 4
SECTIONS 1 & 2
Work, Power and
Machines
1. What is work?
• A. The type of energy that a moving object
has
• B. The rate at which work is done or
energy is transformed
• C. The unit used to express power
• D. The transfer of energy using a force that
causes an object to move in the direction of
the force
ANSWER:
•Work is…
• D. The transfer of energy using a
force that causes an object to
move in the direction of the force
2. What is power?
• A. The type of energy that a moving object
has
• B. The rate at which work is done or
energy is transformed
• C. The unit used to express power
• D. The transfer of energy using a force that
causes an object to move in the direction of
the force
ANSWER
• Power is…
• B. The rate at which work is done or
energy is transformed
3. What is kinetic energy?
• A. The type of energy that a moving object
has
• B. The rate at which work is done or
energy is transformed
• C. The unit used to express power
• D. The transfer of energy using a force that
causes an object to move in the direction of
the force
ANSWER
• Kinetic energy is …
• A. The type of energy that a moving
object has
4. What is a machine?
• A. The type of energy that a moving object
has
• B. The rate at which work is done or energy is
transformed
• C. A device that helps do work by either
overcoming a force or changing the direction
of the force
• D. The transfer of energy using a force that
causes an object to move in the direction of
the force
ANSWER
•A machine is…
• C. A device that helps do work by
either overcoming a force or changing
the direction of the force
5. What is work input?
• A. A number that tells how many
times a machine multiplies a force
• B. A quantity, usually expressed as a
percentage, that measures the ratio of
work output to work input
• C. The work done ON a machine
• D. The work done BY a machine
ANSWER
•Work input is…
• C. The work done ON a machine
6. What is work output?
• A. A number that tells how many
times a machine multiplies a force
• B. A quantity, usually expressed as a
percentage, that measures the ratio of
work output to work input
• C. The work done ON a machine
• D. The work done BY a machine
ANSWER
• Work output is…
• D. The work done BY a machine
7. What is mechanical advantage?
• A. A number that tells how many
times a machine multiplies a force
• B. A quantity, usually expressed as a
percentage, that measures the ratio
of work output to work input
• C. The work done ON a machine
• D. The work done BY a machine
ANSWER
Mechanical advantage is…
• A. A number that tells how many
times a machine multiplies a force
8. What is mechanical efficiency?
• A. A number that tells how many
times a machine multiplies a force
• B. A quantity, usually expressed as a
percentage, that measures the ratio
of work output to work input
• C. The work done ON a machine
• D. The work done BY a machine
ANSWER
Mechanical efficiency is…
• B. A quantity, usually expressed
as a percentage, that measures
the ratio of work output to work
input
9. In which situation is a person doing
work on an object?
• A.
A school crossing guard raises a stop
sign that weighs 10 N.
• B. A student walks while wearing a
backpack that weighs 15 N.
• C. A man exerts 350 N force on a rope
attached to a house.
• D. A worker holds a box 1 m off the floor.
ANSWER
• A. A school crossing guard raises
a stop sign that weighs 10 N.
10. Scott applies a force of 100 N to move
a box 5 meters. How much work did he
do?
• A. 100 J
• B. 500 J
• C. 5 J
• D. 500 N
ANSWER
•B. 500 J
11. If a barbell weighs 160 N, what other
information do you need to calculate how
much work it takes to lift it?
• A.
The shape of the weights
• B. The height the barbell is being lifted
• C. The strength of the person doing the
lifting
• D. The amount of output force
ANSWER
• B. The height the barbell is being
lifted
12. Tom used 75 N of force to push a box
3 m across the floor. How much work did
he do?
a. 25 J
b. 25 N
c. 225 J
d. 225 W
ANSWER
75 N x 3 m =
c. 225 J
13. Which of the following prevents
machines from being 100% efficient?
a. friction
b. input force
c. output force
d. power
ANSWER
a. friction
GOOD LUCK ON TUESDAY!!
STUDY HARD!!
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