Unit 6 Test Review

A ball is thrown up into the air. What is true about its total energy at any point during its flight? (AKS 5b)

• Total Energy = KE x PE

• Total Energy = KE - PE

• Total Energy = KE / PE

• Total Energy = KE + PE

Answer explanation

The total energy of the ball is the sum of its kinetic energy (KE) and potential energy (PE) at any point in its flight. Therefore, the correct relationship is Total Energy = KE + PE.

Tags

NGSS.MS-PS3-5

A wagon has a mass of 5.00 kg. A worker pulls the wagon across a field at a velocity of 1.5 m/s. What is the kinetic energy of the wagon? (AKS 5b1)

• 0 J

• 7.5 J

• 5.625 J

• 22.5 J

Answer explanation

The kinetic energy (KE) is calculated using the formula KE = 0.5 * m * v^2. Substituting the values, KE = 0.5 * 5.00 kg * (1.5 m/s)^2 = 5.625 J. Thus, the correct answer is 5.625 J.

Tags

NGSS.MS-PS3-1

What happens to the potential and kinetic energy as an object falls to the ground? (AKS 5b)

• KE increases, PE decreases

• KE decreases, PE increases

• KE increases, PE increases

• KE decreases, PE decreases

Answer explanation

As an object falls, its potential energy (PE) decreases due to a reduction in height, while its kinetic energy (KE) increases as it accelerates towards the ground. Thus, the correct choice is KE increases, PE decreases.

Tags

NGSS.MS-PS3-5

What is the relationship between work and power? (AKS 5c)

• Work is applying a force through a distance to move an object, while power is using an energy transfer to move an object.

• Work is transferring energy by applying a force through a distance to move an object, and power is the rate at which (how quickly) energy is transferred.

• Power is transferring energy by applying a force through a distance to move an object, and work is the rate at which (how quickly) the energy is transferred.

• Work is applying a force on an object, while power is transferring energy to an object.

Answer explanation

The correct choice explains that work involves transferring energy by applying a force over a distance, while power measures how quickly this energy transfer occurs, highlighting their distinct yet related concepts.

Tags

NGSS.MS-PS3-5

NGSS.MS-PS3-4

What is the missing value for the gravitational potential energy of the ball in the diagram below? (AKS 5b)

• 50 J

• 0 J

• 20 J

• 30 J

Answer explanation

The gravitational potential energy (GPE) is calculated using the formula GPE = mgh. Given the values in the diagram, the calculation results in 30 J, making it the correct answer.

Tags

NGSS.MS-PS3-2

NGSS.MS-PS2-4

A 55-kg crate is lifted to a height of 22 m above the ground. How much work is done on the crate? (AKS 5b2)

• 490 J

• 1,780 J

• 11,858 J

• 1,078 J

Answer explanation

The work done on the crate is calculated using the formula: Work = mass × gravity × height. Here, Work = 55 kg × 9.8 m/s² × 22 m = 11,858 J. Thus, the correct answer is 11,858 J.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS2-4

A 208-kg boulder is at rest on the edge of a cliff that is 25 m high before it comes loose and falls freely downward. What is the potential energy of the boulder just as it starts to fall from the top of the cliff? (AKS 5b1)

• 0 J

• 4455 J

• 43,659 J

• 50,960 J

Answer explanation

The potential energy (PE) is calculated using the formula PE = mgh, where m = 208 kg, g = 9.81 m/s², and h = 25 m. Thus, PE = 208 kg * 9.81 m/s² * 25 m = 50,960 J, making the correct answer 50,960 J.

Tags

NGSS.MS-PS3-2

What is the kinetic energy of the boulder at the top of the cliff before it starts to fall? (AKS 5b1)

• 0 J

• 2.0 J

• 43,659 J

• 50,960 J

Answer explanation

The kinetic energy of an object is given by the formula KE = 1/2 mv². At the top of the cliff, before the boulder begins to fall, its velocity (v) is 0 m/s. Therefore, the kinetic energy is 0 J.

A 208-kg boulder is at rest on the edge of a cliff that is 25 m high before it comes loose and falls freely downward. What is the potential energy of the boulder just as it starts to fall from the top of the cliff? What is the kinetic energy of the boulder at the bottom of the cliff just before it hits the ground? (AKS 5b1)

• 0 J

• 4455 J

• 43,659 J

• 50,960 J

Answer explanation

The potential energy (PE) is calculated using PE = mgh. Here, m = 208 kg, g = 9.81 m/s², and h = 25 m. Thus, PE = 208 * 9.81 * 25 = 50,960 J. This is the correct answer as it represents the energy at the top of the cliff.

Tags

NGSS.MS-PS3-5

NGSS.MS-PS3-2

NGSS.MS-PS3-4

The skateboarder shown below has a potential energy of 2,800 J at her starting height of 4 meters. How much potential energy (PE) and kinetic energy (KE) will she have when she is halfway down (2 meters above the bottom of the ramp)?

• 2800 J

• 1400 J

• 0 J

Answer explanation

At 4 meters, the skateboarder has 2800 J of potential energy (PE). At 2 meters, she has half that PE, which is 1400 J. The kinetic energy (KE) increases by the same amount, so PE is 1400 J and KE is 1400 J.

Tags

NGSS.MS-PS3-5

NGSS.MS-PS3-2

NGSS.MS-PS3-4