Physics Kinetic Energy

What is the speed of an object of 1kg mass with a kinetic energy of 50J?

• 1000 Joules

• 10 Joules

• 10 m/s

• 100 m/s

Tags

NGSS.HS-PS3-2

During a game of pool, the cue ball is rolling toward the eight ball that is at rest. Preeta claims that all of the kinetic energy in the cue ball will get transferred to the eight ball after they collide. Which graph best supports Preeta’s claim?

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Tags

NGSS.HS-PS3-2

Why did the racquetball bounce higher when bouncing from the basketball than when it was originally dropped?

• The racquetball bounced higher because it started from a higher position on the basketball.

• Both the racquetball and the basketball had increased kinetic energy when they were bounced together.

• The racquetball bounced higher because energy was transferred to it from the basketball. The basketball then bounced lower than it did on its own.

• The racquetball bounced to the same height regardless of where it starts.

Answer explanation

The racquetball bounced higher because it received energy from the basketball during the collision. This energy transfer allowed the racquetball to achieve a greater height than when it was dropped alone.

Tags

NGSS.MS-PS2-2

NGSS.MS-PS3-1

NGSS.MS-PS3-5

The diagram shows how one type of energy can be converted to another type of energy. In this case, KE is converted to GE which gets converted back to KE. The racquetball/basketball demonstration showed that energy can also be transferred from one object to another within a system. Consider the pendulum and the surrounding air molecules as a system. Which energy transfer diagram shows what causes the pendulum to slow down and eventually stop?

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Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

Why does a ball stop bouncing?

• Each time a ball hits the floor the KE gets converted to GE and some is lost to gravity. The GE gets transferred to KE and then to Elastic Energy. Friction also plays a role.

• The ball stops bouncing because each time it strikes the ground some of its energy is transferred to the surroundings, so less remains for the ball. This continues until none remains for the ball and then it stops.

• The ball stops bouncing because each time it strikes the floor the elastic energy absorbs the shock. The KE and GE decrease over time until it slows down and stops.

Answer explanation

The ball stops bouncing because each time it strikes the ground, some energy is lost to the surroundings. This energy loss continues until there is none left for the ball, causing it to stop.

Tags

NGSS.MS-PS3-1

NGSS.MS-PS3-5

Which energy transfer diagram represents the racquetball and basketball demonstration?

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Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

NGSS.MS-PS3-1

NGSS.MS-PS3-5

What causes the pendulum to slow down and eventually stop?

• The pendulum slows down and eventually stops because it transfers kinetic energy to the surrounding air molecules.

• The pendulum slows down and eventually stops because gravity pulls it down toward the center of the Earth.

• The GE of the pendulum gets transferred to the air around the pendulum and causes it to stop.

Answer explanation

The correct choice explains that the pendulum slows down due to the transfer of kinetic energy to surrounding air molecules, leading to energy loss and eventual stop, rather than gravity or potential energy transfer.

Tags

NGSS.MS-PS3-5

How does friction affect the motion of a sliding object?

• a. Friction increases the speed of the sliding object.

• b. Friction decreases the speed of the sliding object.

• c. Friction has no effect on the speed of the sliding object.

• d. Friction converts kinetic energy into potential energy.

Answer explanation

Friction opposes the motion of sliding objects, causing them to slow down. Therefore, the correct answer is b: Friction decreases the speed of the sliding object.

Tags

NGSS.MS-PS3-5

You are traveling along a freeway at 65 mi/h; your car has kinetic energy. You suddenly skid to a stop because of congested traffic. What happened to the kinetic energy your car just had?

• It is all in internal energy in the road

• It is all in internal energy in the tires

• Some of it has transformed to internal energy for the tires and the road, and some of it transferred away by sound energy and thermal energy into the air.

• It was destroyed

Tags

NGSS.HS-PS3-4

A major league pitcher can throw a baseball with a kinetic energy of 150 J. How much work must the pitcher do to the ball to give it that much KE?

• 150 J

• 0

• Can’t tell without knowing the mass of the ball

Tags

NGSS.HS-PS3-1