AnswersLHS Physical ScienceUnit Test

Unit Test — Unit test Answers

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1
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What is needed for work to be done?

A
A force must push on an object without moving it.
B
A force must pull on an object without moving it.
C
A force must cause an object to move along the same direction as the force.
D
A force must act on an object while an equal force acts oppositely on the object.
2
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What is the unit of measure for energy?

A
watt
B
newtons
C
joules
D
meters per second
3

How does using a ramp make work easier when loading a piano onto a truck three feet above the ground?

A
It allows a larger force to be applied over a shorter distance.
B
It allows a larger force to be applied over a longer distance.
C
It allows a smaller force to be applied over a shorter distance.
D
It allows a smaller force to be applied over a longer distance.
4

Which simple machine is best used to split apart an object?

A
a screw
B
a lever
C
a wedge
D
a pulley
5

A wheelbarrow can be used to help lift a load, such as a pile of dirt, and then push the load across a distance.

Question illustration
A
a pulley and an inclined plane
B
a wheel and axle and a lever
C
a pulley and a wheel and axle
D
a lever and a wedge
6

A powered winch is used to pull a sailboat to shore. The winch uses a 900 W motor.If the motor is used for 30 s, how much work does it do? (Power: P = W/t)

A
0.03 J
B
30 J
C
960 J
D
27,000 J
7

When a spring is compressed, the energy changes from kinetic to potential. Which best describes what is causing this change?

A
work
B
power
C
gravitational energy
D
chemical energy
8

Seema knows the mass of a basketball. What other information is needed to find the ball’s potential energy?

A
the volume and height the ball reaches
B
the volume and shape of the ball
C
acceleration due to gravity and the height the ball reaches
D
acceleration due to gravity and the shape of the ball
9

A machine has an efficiency of 80%. How much work must be done on the machine so to make it do 50,000 J of output work?

A
12,500 J
B
40,000 J
C
62,500 J
D
90,000 J
10

Which set of terms best defines what affects kinetic energy and potential energy, respectively?

A
position, gravity
B
gravity, velocity
C
velocity, height
D
height, position
11

Simone created a chart to summarize the energy transformations that take place when energy from the wind is used to generate electricity.Which best completes the chart?

Question illustration
A
nuclear energy transformed to electrical energy
B
chemical energy transformed to electrical energy
C
radiant energy transformed to mechanical energy
D
kinetic energy transformed to mechanical energy
12

As a person pushes a box across a floor, the energy from the person’s moving arm is transferred to the box, and the box and the floor become warm. During this process, what happens to energy?

A
It is increased.
B
It is conserved.
C
It is decreased.
D
It is created.
13

The table shows information about four students who are running around a track. Which statement is supported by the information in the chart?

Question illustration
A
Autumn has more kinetic energy than Chiang.
B
Mohammed has less kinetic energy than Autumn.
C
Lexy has more kinetic energy than Mohammed.
D
Chiang has less kinetic energy than Lexy.
14

What is the mechanical advantage of a pulley that changes only the direction of the load, not the effort force?

A
0.5
B
1.0
C
1.5
D
2.0
15

Keisha is making a diagram of a simple machine in the body.

Question illustration
A
X: loadY: fulcrumZ: lever
B
X: fulcrumY: wedgeZ: load
C
X: wedgeY: fulcrumZ: load
D
X: leverY: loadZ: fulcrum
16

If the kinetic and potential energy in a system are equal, then the potential energy increases. What happens as a result?

A
Total energy increases.
B
Stored energy decreases.
C
Energy of motion decreases.
D
Total energy decreases.
17

Adita lifts a book from the floor, carries it across the room, and places it on a high shelf. When is Adita doing work on the book?

A
She does work on the book at no time during this process.
B
She does work only while she carries the book across the room.
C
She does work from the moment she touches the book until she lets it go.
D
She does work as she picks up the book and as she lifts it to the shelf.
18

Which term is the product of force and distance?

A
power
B
work
C
net force
D
acceleration
19

Which statement describes how a machine can help make work easier?

A
It can put out more force than the input force by decreasing the distance over which force is applied.
B
It can increase the amount of work performed if the output force is in the same direction as the input force.
C
It can apply a greater output force over a greater distance compared to the input force and distance.
D
It can increase the distance over which output force acts by applying less output force than input force.
20

Which refers to the ratio of output force to input force of a machine?

A
mechanical advantage
B
average strength
C
total power
D
energy requirement

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