physics 7

The force between the charges q₁ and q₂ is ​ ​ (a)  

• repulsive
• attractive

What happens to the potential energy of this system as charge #2 is moved away from charge #1?

• it increases

• it decreases

• it remains the same

Which best supports that the potential energy will decrease as charge 2 is moved toward charge 1?

• The magnitude of each charge is constant

• opposite charges naturally attract each other

• electric charges release energy when they are in motion

• an external force is required to move the charges together

The force between charges q₁ and q₂ is ​ (a)  

• repulsive
• attractive

The forces are repulsive when the magnitude doubles for both charges q1 and q2, the force between the two charges becomes​ (a)  

• four times greater
• one quarter of what it was

Assume that the force of gravitational attraction between two objects is 18 units.

What will the force of gravitational attraction between the objects be if the mass of both objects doubles and the distance between the objects doubles?

• 9 units

• 18 units

• 36 units

• 72 units

A 68-kg woman exerts 20 Newtons of force against a 12-kg box.How many Newtons of force does the box exert on the woman? (Use only the numeral keys to submit your answer. Do not include units.)

A 40-kg boy exerts 10 Newtons of force against a 45-kg boy who is standing still. How many Newtons of force does the the second boy exert on the first boy? (Use only the numeral keys to submit your answer. Do not include units.)

A student built a simple electromagnet. He performed an experiment to determine how the number of loops around the magnet affected the number of paperclips held by the magnet. His data is shown on the table at the left.

What is the best prediction for the maximum number of paperclips the electromagnet will hold with 50 loops of wire around the nail?

• 22

• 25

• 28

• 32

A 1-kg book exerts 5 Newtons of force down on the 40-kg table on which it rests. How many Newtons of force does the table exert on the book? (Use only the numeral keys to submit your answer. Do not include units.)

• 1

• 5

• 40

• 200