4th SCI_Unit 1 Review

What is a force that pulls objects toward the center of the Earth?

• Friction

• Gravity

• Balanced force

• Push

True or False: UNBALANCED FORCES create a change in motion.

• True

• False

What do BALANCED FORCES do to an object?

• They move the object in the direction of the greatest force.

• They produce a change in motion.

• They do not produce a change in motion.

• They always result in movement.

What is a simple machine that has a gently sloped surface to move objects upward with less force?

• Lever

• Pulley

• Inclined plane

• Screw

What are COMPOUND MACHINES?

• Machines that use gravity to work

• Simple machines that make work harder

• Two or more simple machines that work together to make work easier

• Machines that can only push objects, not pull

What is a SCREW in terms of simple machines?

• A simple machine that uses friction to move objects

• An inclined plane wrapped around a center rod

• A machine that changes the direction of a force

• A lever that rotates around a fixed point

What is a wedge?

• A simple machine that gets thinner at one end and is used to split material.

• A plank that rests on something and moves up and down.

• A wheel and axle that changes the direction of a force.

• A simple machine used to move objects across a distance.

What is an example of a lever?

• A knife.

• A seesaw.

• A flagpole.

• A bicycle wheel.

What does a pulley do?

• Splits material such as wood.

• Moves up and down on a plank.

• Changes the direction of a force.

• Holds two pieces of wood together.

Which of the following is an example of a wheel and axle?

• A knife.

• A seesaw.

• A flagpole.

• The wheel on a bicycle or a car.