Roelfs Force and Motion Test

If an object is not moving, what must happen for it to start moving?

• An outside force must act upon it
• The mass of the object must be increased
• The weight of the object must be decreased
• All forces acting on the object must be balanced

The force that pulls falling objects toward Earth is called _______.

• air resistance
• free fall
• acceleration
• gravity

The unit of measure for force is a _______.

• meter
• pound
• newton
• kilogram

When forces are balanced, the net force is _____.

• greater than the sum of the forces
• zero
• negative
• greater than zero

Which of the following is an example of acceleration?

• A car stopped at a red light
• a truck traveling 65 mph north
• a person jogging at 3 meters/second along a winding path
• a boat sailing south at 5 knots

An object’s gravitational force depends primarily on the object’s _______.

• density
• momentum
• mass
• volume

The rate at which velocity changes is called _______.   

• speed
• direction
• acceleration
• motion

The tendency of an object to resist any change in its motion is known as _______.

• a balanced force
• an unbalanced force
• work
• inertia

Which explains what happens to the force of gravity between two objects is the distance between them decreases?

• Gravity disappears
• Gravity increases
• Gravity decreases
• Gravity remains the same

The force you have to overcome to start an object moving is _________.

• rolling friction
• sliding friction
• static friction
• air resistance