Energy Review Test

Jose is practicing his throws with the Bulldogs. What happens to the ball's energy when Jose releases it?

• Kinetic energy is transferred from the air to the ball.

• Kinetic energy is transferred from Jose's hand to the ball.

• Potential energy is transferred from the ball to Jose's hand.

• Potential energy is transferred from the air to the ball.

Answer explanation

When Jose releases the ball, kinetic energy from his hand is transferred to the ball, causing it to move. This is why the correct answer is that kinetic energy is transferred from Jose's hand to the ball.

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Based on the graph, how does the gravitational potential energy change with the mass of an object?

• Gravitational potential energy remains constant as mass increases.

• Gravitational potential energy decreases as mass increases.

• Gravitational potential energy increases as mass increases.

• Gravitational potential energy is not affected by changes in mass.

Answer explanation

Gravitational potential energy is directly proportional to mass. Thus, as mass increases, potential energy increases.

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A 500-kilogram wrecking ball is hanging motionless from a crane. Which of the following best describes its kinetic energy at this point?

• It has zero kinetic energy at at this point

• It has some kinetic energy at this point

• It has zero potential energy at this point

• There is no way to know how much kinetic energy it has at this point

Answer explanation

The wrecking ball is hanging motionless, meaning it is not moving. Kinetic energy is the energy of motion, so if the ball is not moving, it has zero kinetic energy at this point.

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NGSS.MS-PS3-1

A 500-kilogram wrecking ball swings from a crane toward a brick wall. When the wrecking ball hits the wall which of the following best describes what happens to the energy?

• Potential energy from the wrecking ball is transformed into kinetic energy which knocks over the wall

• Kinetic energy from the wrecking ball is transformed into potential energy which knocks over the wall

• Potential energy from the wrecking ball is transferred to the wall which knocks over the wall

• Kinetic energy from the wrecking ball is transferred to the wall which knocks over the wall

Answer explanation

When the wrecking ball strikes the wall, its kinetic energy is transferred to the wall, causing it to collapse. This choice accurately describes the energy transfer during the impact.

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In a baseball game, the pitcher throws the ball, and the batter hits it. The ball flies over the field and lands in the stands. Which of the following energy transformations occur during this event? Select the 3 that apply.

• The total energy of the system is conserved throughout the event.

• The total energy of the system increases during the event.

• Some of the kinetic energy is converted into sound energy when the ball is hit.

• Some of the potential energy is converted into electrical energy as the ball travels.

• Some of the kinetic energy is converted into thermal energy due to air resistance.

Answer explanation

The total energy is conserved as energy cannot be created or destroyed. Kinetic energy converts to sound energy when the bat hits the ball, and some kinetic energy is lost as thermal energy due to air resistance.

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Jenna's brother loves to slide down the slide at the playground. Which statement is true about the transformation between kinetic and potential energy as he slides down?

• Potential energy changes to kinetic energy between points A and B.

• Kinetic energy changes to potential energy between points A and B.

• Potential energy changes to kinetic energy between points B and C.

• Potential and kinetic energy remain constant between points A and C.

Answer explanation

As Jenna's brother slides down, his height decreases, leading to a decrease in potential energy. This energy is converted into kinetic energy, which increases his speed. Therefore, potential energy changes to kinetic energy between points A and B.

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Which graph best represents the relationship between kinetic energy and speed?

• Graph A

• Graph B

• Graph C

• All of the above could possibly represent Kinetic energy and speed depending on the object.

Answer explanation

Graph A correctly shows that kinetic energy (KE) is proportional to the square of speed (v), represented by the equation KE = 1/2 mv^2. As speed increases, kinetic energy increases quadratically, making Graph A the best representation.

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NGSS.MS-PS3-1

A lion cub and an adult lion are running across a field at the same speed. The lion cub has half the mass of the adult lion. How does the kinetic energy of the lion cub compare to the kinetic energy of the adult lion?

• The cub has a quarter the kinetic energy of the adult.

• The cub has half the kinetic energy of the adult.

• The cub has twice the kinetic energy of the adult.

• The cub has four times the kinetic energy of the adult.

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Aria and Oliver are at an amusement park. Which of the following is displaying gravitational potential energy?

• a stretched rubber band

• a bicycle lying on the ground

• a rollercoaster at the top of a 50 meter high track

• a large rock sitting at rest on the ground

Answer explanation

Gravitational potential energy is stored in an object due to its height. The rollercoaster at the top of a 50 meter high track has significant gravitational potential energy because of its elevated position compared to the ground.

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NGSS.MS-PS3-2

Sara is doing an obstacle course. She reaches a ladder and climbs down to the ground. How did Sara change her gravitational potential energy?

• Her gravitational potential energy decreased.

• Her gravitational potential energy increased.

• The gravitational potential energy between Sara and Earth did not change.

Answer explanation

As Sara climbs down the ladder, she moves closer to the ground, reducing her height relative to Earth. This decrease in height results in a decrease in her gravitational potential energy.

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