What are forces?

What surface would probably offer the least friction if you were to slide a box across it?

• glass
• wood
• carpet
• brick

Which describes friction?

• a unit that is a measure of speed
• a force that works against gravity
• a form of energy that depends on light and heat
• a force that opposes motion between two surfaces that are touching

The force of gravity acting on an object is the object's ______.

• Mass
• Matter
• Weight 
• Terminal velocity 

The rougher the surface, the faster an object will travel over the surface.

• True
• False

A boblsed glides across the ice and gradually begins to slow down.  Which force acts opposite to the bobsled's motion?

• lift
• weight
• gravity
• friction

What two forces act on a skydiver?

• Gravity and Air resistance
• Gravity and Falling friction
• Gravity and static fricion
• Gravity and pull

A car traveling down the road approaches a red light.  The driver pushes the car's brakes and the car slows to a stop.  What causes the car's speed to change?

• a decrease in velocity
• an increase in velocity
• an increase in friction
• a decrease in friction

What force keeps a satellite in orbit?

• gravity
• friction
• electricity
• magnetism

What is a force?

• Motion
• Work
• Push or a pull
• What Luke Skywalker does

When is there a change in motion?

• When the forces are balanced.
• When the forces are unbalanced.
• Never.
• When the forces are equal.