Conservation of Energy

There are three shelves in a closet. The first one is 1.5 meters above the floor, the second shelf is 2.0 meters above the floor, and the third shelf is 2.5 meters above the floor.

A 10 kg box rests on the first shelf. How much gravitational potential energy does the box have relative to the second shelf?

• 50 J

• 100 J

• 150 J

• 200 J

Tags

NGSS.MS-PS3-2

NGSS.MS-PS2-4

There are three shelves in a closet. The first one is 1.5 meters above the floor, the second shelf is 2.0 meters above the floor, and the third shelf is 2.5 meters above the floor.

The box is lifted to the third shelf. How much gravitational potential energy does the box have relative to the first shelf?

• 100 J

• 50 J

• -50 J

• 150 J

Tags

NGSS.HS-PS3-1

A roller coaster uses a motor to take a car to the top of its first hill. The roller coaster then travels down a 35 meter hill and to the top of the next hill. It travels with a speed of 15 m/s at the top of the second hill.

How high is the second hill? Assume no energy is lost to friction and the coaster starts from rest at the top of the first hill.

• 12.5 m

• 24 m

• 34 m

• This cannot be determined without the mass of the car.

Tags

NGSS.HS-PS3-1

In July 1971, Apollo 15 astronaut Dave Scott performed an experiment on the Moon. Scott held a feather and a hammer at the same height, and let them drop at exactly the same time. Both fell at the same rate and hit the ground at the same time.

At which time did the feather have the greatest kinetic energy?

• time 1

• time 2

• time 3

• both times 1 and 3

Tags

NGSS.HS-PS2-1

In July 1971, Apollo 15 astronaut Dave Scott performed an experiment on the Moon. Scott held a feather and a hammer at the same height, and let them drop at exactly the same time. Both fell at the same rate and hit the ground at the same time.

At which time did the hammer have the greatest gravitational potential energy?

• time 1

• time 3

• times 1 and 3

• time 2

Tags

NGSS.MS-PS3-2

NGSS.MS-PS2-4

NGSS.MS-PS2-5

In July 1971, Apollo 15 astronaut Dave Scott performed an experiment on the Moon. Scott held a feather and a hammer at the same height, and let them drop at exactly the same time. Both fell at the same rate and hit the ground at the same time.

Which of the following is true about the relationship between the gravitational potential energy and the kinetic energy of the hammer?

• The kinetic energy + gravitational potential energy stays the same at all times.

• The kinetic energy and potential energy are the same as each other at all times.

• The kinetic energy at time 1 is equal to the gravitational potential energy at time 1.

• The kinetic energy at time 3 is equal to the gravitational potential energy at time 3.

Tags

NGSS.MS-PS3-2

NGSS.MS-PS2-4

NGSS.MS-PS3-5

An apartment building has two floors and a basement. The floors are 3.5 meters apart and the basement is 2.5 meters underground as shown.

A 100 kg man enters the apartment building at the ground floor and walks up to his second floor apartment. How much gravitational potential energy does he have relative to the ground? Use g = 10 m/s².

• 350 J

• 700 J

• 3500 J

• 7000 J

Tags

NGSS.HS-PS3-1

NGSS.HS-PS2-4

An apartment building has two floors and a basement. The floors are 3.5 meters apart and the basement is 2.5 meters underground as shown.

The man’s 50 kg son is in the basement doing laundry. How much gravitational potential energy does the son have relative to his father on the second floor? Use g = 10 m/s².

• -3000 J

• -300 J

• 300 J

• 3000 J

Tags

NGSS.HS-PS3-1

A crate slides down a 5-meter-long, 2-meter-high ramp as shown.

Alli places the 35 kg crate at an undesignated height and lets it slide to the bottom. Her lab partner measures the speed at the bottom of the ramp to be 5.5 m/s. Assuming the ramp is frictionless, at what height did Alli release the crate? Use g = 10 m/s².

• 1.5 m

• 2.0 m

• 0.5 m

• 1.0 m

Tags

NGSS.HS-PS3-1

A temporary ladder can be used to escape from an upper story window in case of fire. The diagram shows a temporary ladder hanging from a second floor window and descending to a deck below. The ladder has 8 steps, each of which is 0.5 meters high. The surface of the deck is 1.0 meters above the ground.

A 10 kg cat is three steps below the window. What is its gravitational potential energy relative to the ground? Use g = 10 m/s².

• -350 J

• -150 J

• 350 J

• 150 J

Tags

NGSS.MS-PS3-2

NGSS.MS-PS2-4