8th grade Final Exam

Ramon 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 not move because the magnets are not touching.

• 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.

Cherise sets identical magnetic carts on two tracks. At the end of each track is a blue magnet that cannot move. Cherise can move the carts one space to the left or one space to the right. Which movement will result in the largest increase in potential energy?

• Moving the cart on Track 1 one space to the right (?).

• Moving the cart on Track 2 one space to the left (?).

• Moving the cart on Track 2 one space to the right (?).

• All these movements will result in the same change in potential energy because they each move a cart the same distance.

Based on the magnetic field line diagrams, what will happen next with these two sets of magnets?

• The magnets in Set 1 will repel, and the magnets in Set 2 will attract.

• The magnets in Set 1 will attract, and the magnets in Set 2 will repel.

• The magnets in Set 1 will not move, and the magnets in Set 2 will attract.

• In both sets, the magnets will attract

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

• The kinetic energy increases as its speed increases.

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

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

• There is no way to know what happens to the kinetic energy.

What happens to the energy in a system of magnets when the magnetic force causes two magnets to move?

• The potential energy in the system increases.

• The kinetic energy in the system decreases.

• Some kinetic energy changes into potential energy.

• Some potential energy changes into kinetic energy.

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.

How does magnetic force affect the energy in a system of magnets when the magnets are released and begin to move?

• The magnetic force increases the potential energy in the system.

• The magnetic force decreases the kinetic energy in the system.

• The magnetic force changes kinetic energy into potential energy.

• The magnetic force changes potential energy into kinetic energy.

Energy can be defined as

• evidence against a claim.

• a push or pull that can change the motion of an object

• a liquid that you put in your car to make it go.

• the ability to make things move or change.

The space around an object in which magnetic forces can act on objects is known as

• its magnetic poles.

• the magnetic field.

• the attraction force.

• the force of repulsion.

What happens when two north poles of a magnet are placed together?

• they repel
• they attract
• they cancel each other out
• the strength of the magnet is doubled