Forces, Electricity, and Magnetism

Motion, Forces, Electricity & Magnetism

by Cecily Vaulx

Multiple Choice

One student rubs a balloon against his hair several times. Another student passes a comb through her hair several times. The students place the comb near the balloon and observe that the comb repels the balloon. Which is the most likely reason the comb is able to repel the balloon?

• The balloon has a positive charge and the comb is neutral.

• The balloon and the comb have the same electrical charge.

• The balloon has a negative charge and the comb is neutral.

• The balloon and the comb have opposite electrical charges.

Multiple Choice

A student attaches a rope to the handle of a chest loaded with a few books, while the other end of the rope is tied to a spring scale. The student pulls the scale with just enough force to set the chest in motion and records the force applied on the spring scale. The student repeats the experiment with more books in the chest and records the data in a table.

What can be concluded from the data?

• As the mass of the chest increases, less force is required to pull it.

• As the mass of the chest increases, more force is required to pull it.

• The amount of frictional force increases as the mass of the chest decreases.

• The amount of frictional force decreases as the mass of the chest increases.

Multiple Choice

A student builds an electromagnet, as shown.

Will the compass needle move when brought near the electromagnet, and why?

• Yes. The needle of a compass changes direction randomly when brought near the electromagnet.

• No. The needle of a compass will not react because the wires are not connected to the battery properly in order to create a working electromagnet.

• No. The needle of a compass only aligns itself with an electric field, which cannot be created by the electromagnet.

• Yes. The needle of a compass aligns itself with the magnetic field created by the electromagnet.

Multiple Choice

The diagram shows a firefighter operating a hose. The arrows show the forces acting on the hose.

Which statement describes the situation in the diagram?

• Since the firefighter is at rest, he does not move as he operates the hose.

• The hose has very little friction, making it slide toward the firefighter.

• The firefighter's mass decreases the force of the water escaping from the hose.

• The water escaping from the hose exerts an equal and opposite force on the hose.

Multiple Choice

When a hammer strikes a nail, the nail

• exerts balanced forces that helps it from moving.

• exerts a force equal to the weight of the hammer.

• exerts an unbalanced force that changes its velocity.

• exerts an equal and opposite force back on the hammer.

Multiple Choice

Use the scenario to answer the question.

Activity 1 Gia pushes two toy cars (1 and 2), each with a different mass, with the same amount of force in the same direction and records the time it takes for each toy car to move two meters, as shown in the table.

Activity 2 Shamiyah pushes Toy Car 1 from two opposite directions at the same time in several trials, as shown.

• Trial 1

• Trial 2

• Trial 3

• Trial 4

Multiple Choice

Cyniah walked the route marked in the diagram from her home at point J to point O.

When Cyniah reaches point O, what is her new position relative to her home at point J?

• 20 meters north

• 25 meters north

• 60 meters north

• 70 meters north

Multiple Choice

A student performs an activity using a sheet of paper, a magnet, and a steel ball. The image shows the setup.

The student observes that the steel ball sticks to the magnet even though the paper is between them. Which factor leads to the attraction of the ball to the magnet?

• The magnet exerts a force on the ball.

• The magnet attracts the paper, which pulls the ball.

• The paper exerts a force on the ball, which pulls the ball toward the magnet.

• The size of the ball attracts the ball toward the magnet.

Multiple Choice

Jazzy designs two electromagnets of different strengths. The first electromagnet has an insulated copper wire wrapped around an iron nail many times before it is connected to a battery. The second electromagnet has its insulated copper wire wrapped around a similar nail a fewer number of times before it is connected to two smaller batteries as shown in the image.

Jazzy tries to determine which electromagnet is stronger by bringing each near a bowl containing eight metal paper clips. She observes that both electromagnets attract all eight of the paper clips.

How can Jazzy demonstrate that each electromagnet has a different strength?

• Place a metal paper clip on a table and slowly bring each electromagnet closer to the paper clip to see which can attract the paper clip from a greater distance.

• Determine which electromagnet has its copper wire wrapped around its iron nail a greater number of times.

• Add plastic paper clips to the bowl and check which electromagnet can attract both kinds of paper clips.

• Reduce the number of paper clips in the bowl and find which electromagnet attracts more paper clips.

  Reduce the number of paper clips in the bowl and find which electromagnet attracts more paper clips.

Multiple Choice

A 100 kg box is initially at rest on a level surface. One 10 N force acts on the box, directed toward the right. A second 10 N force acts simultaneously on the box, directed toward the left, as shown.

How is the box affected by the two forces?

• The box will move because unbalanced forces are acting on it.

• The box will move because balanced forces are acting on it.

• The box will not move because unbalanced forces are acting on it.

• The box will not move because balanced forces are acting on it.

Multiple Choice

Four smooth blocks are being pushed along a smooth surface. The diagram shows the mass of the blocks and the force applied to each block.

What can be concluded about the motion of the blocks?

• Block 1 will move the farthest.

• Block 1 will move farther than Block 3.

• Blocks 2 and 3 will not move.

• Block 4 will move farther than Block 2.

Multiple Choice

Would increasing the number of batteries in a circuit that is connected to a small electric motor affect the speed of the motor, if all other variables are kept constant?

• No, because it is the magnetic force, not the electric force, that controls the motor speed.

• Yes, the motor would run faster because the increased electrical force increases the magnetic force in the motor.

• No, the speed of a motor is controlled only by the number of wire coils in the motor.

• Yes, the motor would run faster because increased current causes the motor to become warmer.

Multiple Choice

Tony is playing with his toy car. A parachute in the back of the car is released to help slow down the car.

If the forces act on the car as shown in the picture, what is the net force?

Multiple Choice

A machine is designed to test the strength of windows. The machine exerts a force on a window, as shown in the diagram.

The window does not break. Which is the correct force diagram that represents the scenario?

Multiple Choice

A student hangs a pith ball from a stand using thread and rubs a glass rod with a silk cloth. Upon bringing the glass rod near the pith ball, the student observes that the pith ball is attracted toward the glass rod, as shown.

How can the observation best be explained?

• The glass rod exerts a gravitational force, causing it to attract the pith ball.

• The pith ball exerts a repulsion force toward the glass rod, causing the attraction.

• An electric field exists between the glass rod and the pith ball, causing the attraction.

• Electric charges in the string transfer to the pith ball, causing it to attract the glass rod.