Magnetic Fields CJ Practice

Select all that apply- which of the following options are not examples of a system?

• Two magnets attracting each other

• A magnet just chilling by itself

• A magnet that is attracted to a box of paper clips

• A ball sitting by itself on a table

Answer explanation

A system is more than one moving part (ie. magnet, object, etc.) working together.

If there is just an object by itself, it is not a system.

Select all that apply- which of the following magnet pairs will have an attracting force?

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Answer explanation

Remember, there is an attracting force between opposite poles! If the poles facing each other are different, they will attract.

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Select all that apply- which of the following magnet pairs will have a repelling force?

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• 

Answer explanation

Remember, there is a repelling force between like poles! If the poles facing each other are the same, they will repel.

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NGSS.MS-PS2-5

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Julia puts two magnetic toy trains very close to each other on a track. What will happen next, and why?

• The trains will move closer to each other because the magnetic force will pull the trains together

• The trains will move away from each other because the magnetic force will push the trains apart.

• The trains will move away from each other because the magnets are not touching.

• The trains will not move because the magnets are not touching.

Answer explanation

Remember, like (same) poles repel (move away from each other).

Since the north poles of both magnets are facing each other, they'll move away from each other, whether or not they are touching.

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In a computer simulation, Juan moves a magnet (Magnet 1) closer to another magnet (Magnet 2) that cannot move. Which statement accurately describes the change in potential energy?

• The potential energy does not change because the magnets in the system do not change.

• The potential energy increases because Magnet 1 moves against the magnetic force.

• The potential energy decreases because Magnet 1 moves against the magnetic force.

• The potential energy decreases because Magnet 1 moves in the same direction as the magnetic force

Answer explanation

Remember, potential energy INCREASES (goes up) the more it moves AGAINST the magnetic force- in other words, it increases when it is forces to go where it doesn't want to go.

Magnets 1 and 2 are repelling each other, and do not want to go closer. When Juan moves Magnet 1 closer to Magnet 2, he is moving it AGAINST the magnetic force.

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NGSS.MS-PS2-5

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Clarisse is moving two magnetic trains on two different tracks. On which track will the magnets have the most potential energy?

• Track 1, because it further away, and therefore moving more against the magnetic force.

• Track 2, because it is closer, and therefore moving more against the magnetic force.

• Track 1, because it further away, and therefore moving more towards the magnetic force.

• Track 2, because it is closer, and therefore moving more towards the magnetic force.

Answer explanation

Potential energy increases as magnets move against the magnetic force- or in the direction they DON'T want to go.

On both tracks, the magnets are repelling. Therefore, the closer the magnets are, the more they are moving against the magnetic force. Therefore, Track 2 has more potential energy.

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The diagram shows the pink magnet at the end of the track that can’t move. When the brown magnet is released, it will move according to the magnetic force from the pink magnet. Answer by stating your answer, evidence from the diagram and an explanation why your answer is correct based on your evidence. 

Part A: Is potential energy increasing or decreasing as the hand slides the brown magnet toward the pink magnet? How do you know?

Answer explanation

Potential energy is increasing! As magnets move against the magnetic force (where they don't want to go), potential energy increases. Therefore, since these magnets repel, moving them closer together moves more potential energy into the system.

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The diagram shows the pink magnet at the end of the track that can’t move. When the brown magnet is released, it will move according to the magnetic force from the pink magnet. Answer by stating your answer, evidence from the diagram and an explanation why your answer is correct based on your evidence. 

Part B: Are these magnets experiencing an attracting or repelling force? How do you know?

Answer explanation

These magnets are receiving a repelling force! This is because like poles (same sides) are facing each other, and like poles repel.

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NGSS.MS-PS2-5

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An airplane is traveling through the air. Suddenly, its speed increases. What can you say about the kinetic energy of the spaceship?

• There is no way to know what happened to the kinetic energy

• The kinetic energy decreases as it is converted into speed.

• The kinetic energy increases as its speed increases.

• The kinetic energy remains the same because speed and kinetic energy are not related

Answer explanation

Kinetic Energy is the energy an object has because it is moving- therefore, as an object speeds up, that means its kinetic energy is also increasing.

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Select the statement that is true for both diagrams:

**Read closely!

• Both diagrams show correct field lines.

• Diagram 2 shows correct field lines but Diagram 1 shows incorrect field lines.

• Both diagrams show incorrect field lines.

• Diagram 2 shows incorrect field lines but Diagram 1 shows correct field lines.

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