Quiz on Gravity and Simple Machines

Which of the following describes the effect of friction?

• It makes objects speed up.

• It opposes motion (correct)

• It causes objects to float.

• It increases weight.

If the distance between two objects increases, what happens to the gravitational force between them?

• Increases

• Decreases (correct)

• Stays the same

• Doubles

On the Moon, a person’s weight is:

• The same as on Earth.

• Less than on Earth (correct)

• Greater than on Earth.

• Unaffected by gravity.

Which of the following is a simple machine?

• Motor

• Lever (correct)

• Engine

• Battery

What type of pulley reduces the effort needed to lift a load?

• Fixed pulley

• Movable pulley (correct)

• Horizontal pulley

• Rigid pulley

Which class of lever has the load in the center?

• Class 1

• Class 2 (correct)

• Class 3

• None of the above

What simple machine is used in a screw?

• Wedge

• Inclined plane (correct)

• Pulley

• Lever

Work is done when:

• Force is applied but no motion occurs.

• An object moves in the direction of the force (correct)

• The object’s weight increases.

• Time is spent applying force.

A machine with high efficiency will:

• Waste a lot of energy.

• Produce more work output than input.

• Produce work output close to the work input (correct)

• Require very little input energy.

Why are modern cars designed with streamlined shapes?

• To reduce air resistance (drag) (correct)

• To make them heavier

• To increase the friction with the ground

• To make them easier to clean