Energy Transformations Review

The diagram below shows a segment of a rollercoaster ride. At various points on the rollercoaster ride, the potential and kinetic energy change. At what point on the rollercoaster is the least amount of gravitational potential energy? (S8P2b, DOK 2)

• W

• X

• Y

• Z

Answer explanation

Point X is the lowest point on the rollercoaster, where gravitational potential energy is at its minimum. As the coaster descends, potential energy decreases and kinetic energy increases, making X the correct answer.

Tags

NGSS.MS-PS3-2

What type of energy transformation occurs when a book falls off a shelf?

• The book's potential energy is converted into kinetic energy.

• The kinetic energy of the book is converted into potential energy.

• The potential energy of the shelf is converted into kinetic energy.

• The kinetic energy of the shelf is converted into potential energy.

Answer explanation

When the book falls, its height decreases, converting its stored potential energy into motion, or kinetic energy, as it accelerates towards the ground.

Tags

NGSS.MS-PS3-2

NGSS.MS-PS3-5

Two students investigate the relationship between potential and kinetic energy. They create an investigation using a pendulum. A student holds the bob in position A and lets go. Which statement correctly describes the relationship between potential and kinetic energy at point B?

• Kinetic and potential energy are increasing.

• Kinetic and potential energy are decreasing.

• Kinetic energy is decreasing, and potential energy is increasing.

• The potential energy is decreasing, and the kinetic energy is increasing.

Answer explanation

At point B, the pendulum bob is moving downward, converting potential energy (due to height) into kinetic energy (due to motion). Therefore, potential energy decreases while kinetic energy increases.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Jackson is visiting a nuclear power plant to learn how electricity is generated. He discovers that the plant transforms nuclear energy into electricity through several steps. It starts with a nuclear reaction that generates heat to produce steam. The steam is then used to turn a generator, which finally produces electricity. Which response best demonstrates this energy transformation?

• nuclear → mechanical → chemical → electrical

• thermal → nuclear → mechanical → electrical

• mechanical → thermal → nuclear → electrical

• nuclear → thermal → mechanical → electrical

Answer explanation

The correct choice is nuclear → thermal → mechanical → electrical. Nuclear energy is first converted to thermal energy through a reaction, then thermal energy produces steam that drives a generator, creating electrical energy.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

When it is very hot in his room, Aiden tries to make it cooler by opening both the top and the bottom of his window. Cooler air comes in through the bottom and warm air goes out through the top. Heat energy is transferred by which of the following processes? (S8P2d, DOK 2)

• radiation

• convection

• conduction

• evaporation

Answer explanation

Heat energy is transferred by convection as cooler air enters from the bottom of the window and warm air exits from the top, creating a circulation of air that cools the room.

A roller coaster starts with 6000 J (Joules) of potential energy at the top of a hill. At the bottom, it has 5000 J of kinetic energy. Which statement best explains what happened to the energy?

• All the energy became kinetic energy.

• All the energy was lost as sound energy.

• Some energy stayed as potential energy.

• Some energy became thermal energy due to air resistance.

Answer explanation

The roller coaster lost some potential energy as it descended. The difference in energy (6000 J - 5000 J = 1000 J) was converted to thermal energy due to friction, explaining the energy loss.

Tags

NGSS.MS-PS3-2

NGSS.MS-PS3-5

Aiden and Zoe are comparing the temperature and thermal energy of the water in Lake Michigan versus a cup of hot cocoa. Which of the following is true?

• The cocoa in the cup has less thermal energy and a lower temperature.

• The cocoa in the cup has more thermal energy and a higher temperature.

• The water in the lake has less thermal energy and a lower temperature.

• The water in the lake has more thermal energy and a lower temperature.

Answer explanation

The water in Lake Michigan, despite being at a lower temperature, contains a vast amount of thermal energy due to its large volume. In contrast, the hot cocoa has a higher temperature but less thermal energy overall.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Why does a tile floor feel colder to the touch compared to a wool rug placed on it?

• Wool is a better thermal insulator than tile.

• Wool is a better thermal conductor than tile.

• Tile is always a lower temperature than wool.

• Wool always contains more thermal energy than tile.

Answer explanation

Wool is a better thermal insulator than tile, meaning it retains heat better. When you touch tile, it draws heat away from your skin more quickly than wool, making it feel colder.

Mr. Smith takes a Stanley cup filled with ice water to work every day. The Stanley cup keeps the water cold by doing which of the following?

• slowing heat transfer

• recirculating hot air inside

• collecting solar heat energy

• using a battery-powered heating pack

Answer explanation

The Stanley cup keeps water cold by slowing heat transfer, which prevents warm air from warming the ice water. The other options do not contribute to maintaining the cold temperature.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-3

Nora is holding a cold piece of metal in her hand. While she is holding the piece of metal, her hand gets colder. Does the piece of metal get warmer? Why or why not?

• Yes, the piece of metal will get warmer because some thermal energy is transferred from the metal to the student's hand.

• Yes, the piece of metal will get warmer because some thermal energy is transferred from the student's hand to the metal.

• No, the piece of metal will stay at the same temperature because an equal amount of thermal energy is exchanged between the student's hand and the metal.

• No, the piece of metal will stay at the same temperature because thermal energy is not transferred between the student's hand and the metal.

Answer explanation

Yes, the piece of metal will get warmer because some thermal energy is transferred from the student’s hand to the metal. As Nora's hand loses heat, the metal absorbs that energy, causing its temperature to rise.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-5