Unit 8.1 Quiz 6

Kinetic energy is:

• a push force.

• the energy carried in light waves.

• the energy of objects in motion.

• the energy stored in food.

Answer explanation

Kinetic energy refers to the energy of objects in motion. It is the energy that an object possesses due to its movement, distinguishing it from other forms of energy like potential energy or energy stored in food.

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NGSS.MS-PS3-1

What two properties of an object affect its kinetic energy?

• mass and weight

• mass and speed

• speed and distance

• weight and height

Answer explanation

Kinetic energy depends on mass and speed. The formula KE = 1/2 mv² shows that both mass (m) and the square of speed (v) directly influence kinetic energy, making 'mass and speed' the correct choice.

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NGSS.MS-PS3-1

What has a larger impact on the kinetic energy of an object and the damage in a collision?

• speed

• mass

• weight

• distance

Answer explanation

Speed has a larger impact on kinetic energy, as it is squared in the kinetic energy formula (KE = 1/2 mv²). Higher speed increases the energy and potential damage in a collision more significantly than mass or weight.

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NGSS.MS-PS3-4

NGSS.MS-PS3-5

When the mass of an object is doubled, the kinetic energy of the object:

• stays the same

• doubles

• triples

• quadruples

Answer explanation

Kinetic energy (KE) is given by the formula KE = 1/2 mv². If the mass (m) is doubled, KE becomes KE = 1/2 (2m)v² = 2(1/2 mv²), which shows that the kinetic energy doubles.

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NGSS.MS-PS3-1

When the speed of an object is doubled, the kinetic energy of the object:

• stays the same

• doubles

• triples

• quadruples

Answer explanation

Kinetic energy (KE) is given by the formula KE = 1/2 mv². When the speed (v) is doubled, the new KE becomes 1/2 m(2v)² = 2mv², which is four times the original KE. Thus, the kinetic energy quadrouples.

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Which graph shows the relationship between kinetic energy and mass?

• A

• B

• C

• D

Answer explanation

Graph D correctly illustrates the relationship between kinetic energy and mass, showing that kinetic energy increases with mass, as represented by a linear relationship in the graph.

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NGSS.MS-PS3-1

Which graph shows the relationship between kinetic energy and speed?

• A

• B

• C

• D

Answer explanation

Graph B correctly illustrates the relationship between kinetic energy and speed, showing that kinetic energy increases with the square of speed, which is represented by a parabolic curve.

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NGSS.MS-PS3-1

Two boats are moving across a lake. The kinetic energy of each boat depends on the boat’s mass and speed. According to the information in the table:

1) The kayak’s mass is ________ the canoe’s mass.

2) The kayak’s speed is _______ the canoe’s speed.

3) The kayak’s kinetic energy is _______ the canoe's kinetic energy.

• 1) the same as; 2) two times; 3) four times

• 1) the same as; 2) half of; 3) four times

• 1) the same as; 2) two times; 3) one-fourth of

• 1) the same as; 2) half of; 3) one-fourth of

Answer explanation

The kayak's mass is the same as the canoe's mass. The kayak's speed is half of the canoe's speed. Kinetic energy is calculated as 1/2 mv^2, so with half the speed, the kayak's kinetic energy is one-fourth of the canoe's.

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