Answers25-26 CHEMISTRY IN THE EARTH SYSTEM S1Conservation of Energy

Conservation of Energy — Unit test Answers

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1
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10152530

A
10
B
15
C
25
D
30
2
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What is the formula for calculating kinetic energy?

A
KE = mv2
Option A
B
KE = 2mv2
C
KE = m2v
Option C
D
KE = 2m2v
3

Why is it important to know the direction of the force applied to a moving object and the direction in which the object is moving when determining the work done on the object?

A
Only the component of the force perpendicular to the motion is used to calculate the work.
B
If the force acts in the same direction as the motion, then no work is done.
C
When there is an angle between the two directions, the cosine of the angle must be considered.
D
A force at a right angle to the motion requires the use of the sine of the angle.
4

If 3,600 J of work is done in 3.0 s, what is the power?

A
0.00083 W
B
1,200 W
C
3,600 W
D
11,000 W
5

Which energy transformations occur in this case? Check all that apply.

A
All of the rocks’ potential energy is converted into kinetic energy because rocks do not experience wind resistance.
B
Some of the potential energy of the feather is converted into kinetic energy.
C
All of the feather’s potential energy is converted into thermal energy due to the friction of air resistance.
D
Some of the rocks’ potential energy is converted into thermal energy due to the friction of air resistance.
E
Some of the feather’s potential energy is converted into thermal energy due to the friction of air resistance.
6

A 60.0 kg object is moving east at 8.00 m/s, and then slows down to 4.00 m/s. How much work was done?

A
–1,440 J
B
–480 J
C
1,440 J
D
2,880 J
7

Four landing sites are proposed for a lander. Data about the sites are listed in the table.

Question illustration
A
W
B
X
C
Y
D
Z
8

A moving company collects data about couches they move and displays the data in a table. The force along the ramp, the angle of the ramp, and the height the couch is raised from the ground to the platform is shown below. Which statements correctly compare the work done to move the couches? Select three options.The same amount of work is done for couches 1 and 3.The same amount of work is done for couches 2 and 3.The work for couch 1 is greater than the work for couch 2.The work for couch 2 is less than the work for couch 3.The work for couch 3 is greater than the work for couch 1.The work for couch 2 is greater than the work for couch 1.

Question illustration
A
The same amount of work is done for couches 1 and 3.
B
The same amount of work is done for couches 2 and 3.
C
The work for couch 1 is greater than the work for couch 2.
D
The work for couch 2 is less than the work for couch 3.
E
The work for couch 3 is greater than the work for couch 1.
F
The work for couch 2 is greater than the work for couch 1.
9

Suppose an object’s initial velocity is 10 m/s and its final velocity is 4 m/s. Mass is constant.What can best be concluded about the object based on the work-energy theorem?

A
Work is positive, the environment did work on the object, and the energy of the system increases.
B
Work is positive, the object did work on the environment, and the energy of the system increases.
C
Work is negative, the object did work on the environment, and the energy of the system decreases.
D
Work is negative, the environment did work on the object, and the energy of the system decreases.
10

Question text not available

Answer not available
11

Four different balls are moving at the same velocity. Which will have the greatest kinetic energy as it rolls?

A
a golf ball
B
a bowling ball
C
a tennis ball
D
a soccer ball
12

Earth and all of the air in the atmosphere around it make up an incredibly complex system. Energy is constantly changing forms in many different ways.

A
Earth is an isolated closed system because energy only escapes the system as heat travels into space.
B
Earth is an isolated closed system because the atmosphere allows energy from the Sun to enter as heat.
C
Earth is an open system because the atmosphere stops energy from escaping into space.
D
Earth is an open system because heat energy from the Sun enters through the atmosphere.
13

The table shows the mechanical energy and velocity of a rock that was thrown four times. The rock has a mass of 2.4 kg.During which trial was the rock the highest above the ground?

Question illustration
A
1
B
2
C
3
D
4
14

The energy transfer diagram represents the energy of a person diving into a pool.

Question illustration
A
1000 J
B
2000 J
C
7000 J
D
15,000 J
15

To do work, this truck uses energy stored in chemical fuel and an electrical battery.

Question illustration
A
50 J
B
250 J
C
400 J
D
800 J

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