Forces of Nature Test 24

Four students are investigating electric motors. They have created an electric motor as shown in the diagram below. Which of the following changes should the students make if the students want to decrease the strength of the motor?

• Increase the voltage of the power source being used to operate the motor.

• Reduce the number of coils of copper wire.

• Change the configuration of the magnets in relation to the copper wire.

• Add a reducer cap to the end of the axle to inhibit movement.

Tags

NGSS.MS-PS2-3

Static electricity happens when electrons pass from one object to another, such as from your hair to a comb as you comb your hair. If you then hold the comb near your hair, strands of hair appear to move forward and "stick to the comb." This is because the hair and the comb –

• have opposite charges.

• have like charges.

• have no charge.

• are magnetic.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

Two charged objects are placed near each other. What happens to them?

• attract each other because they have opposite charges.

• attract each other because they have the same charges.

• repel each other because they have opposite charges.

• repel each other because they have the same charges.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

Two oppositely charged objects are separated by a small distance. The objects are then moved three times farther apart from each other. Which of the following statements best describes what happens to the electrical force between the objects?

• The force of attraction increases.

• The force of attraction decreases.

• The force of attraction becomes zero.

• The force of attraction remains the same.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

A student is completing a lab investigation as shown in the diagram.

Why does the top magnet appear to float above the bottom magnet?

• Magnet A is made from a different material than Magnet B.

• The opposite poles of the magnets are facing each other.

• The like poles of the magnets are facing each other.

• The magnets have a different gravitational attraction.

Tags

NGSS.MS-PS2-5

Each diagram shows two pith balls (foam balls coated with aluminum) hanging from strings. A pith ball can be given a positive (+) or a negative (-) electrical charge. Which of the following diagrams shows a correct way in which the charged balls will be attracted to or repelled by each other?

• 
• 
• 
• 

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

Look at the diagram of the bar magnets.

What will happen to the force between the two magnets

if they are pulled farther apart?

• The force will increase.

• The force will decrease.

• The force will remain the same.

• The force will fluctuate.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

What will happen to the repelling force when the attracting force is stronger?

• The repelling force will remain the same.

• The attracting force will be stronger.

• The repelling force will be weaker.

• The attracting force will reverse the poles.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

A positively charged pith ball, K, is hung from a ring stand. You hold a glass rod in your hand; your partner rubs the glass rod with a piece of silk cloth. Next you approach the pith ball very slowly with the glass rod. The results can be seen here. State an appropriate conclusion for this investigation.

• The positive charge from K is transferred to the glass rod.

• The glass rod acquired a positive charge from the silk; like charges repel and K moves away.

• The glass rod acquired a positive charge from the silk and that charge was transferred to K.

• The glass rod acquired a negative charge from the silk; opposite charges repel and K moves away.

Tags

NGSS.MS-PS2-3

A force is a push or pull on an object that could affect its motion. Which is an example of a non-contact force?

• drag force

• spring force

• friction force

• magnetic force

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-4

NGSS.MS-PS2-5