Module 2

the law of inertia applies to

both stationary and moving objects

According to Newton's law of inertia, a railroad train in motion should continue going forever even if its engine is turned off. We never observe this because railroad trains

Always have forces that oppose their motion

If you slide a hockey puck across a frictionless patch of ice, there must be a horizontal force on it to keep it in motion. (T/F)

False

An object following a straight-line path at constant speed

Has zero acceleration

A moving body must undergo a change in

Position

A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This best demonstrates that

The milk carton has inertia

Inertia is the property that every material object has that causes the object to resist changes in its state of motion. Mass is a measure of inertia (T/F)

True

The reason a penny thrown straight up inside a bus will come back to your hand is that you, the bus, the air inside the bus, and the penny are all moving at the same velocity.

True

If no external forces are acting on a moving object, it will

continue moving at the same velocity

A truck is moving at a constant velocity. Inside the storage compartment, a rock is dropped from the midpoint of the ceiling and strikes the floor below. The rock hits the floor

exactly below the midpoint of the ceiling

if a hockey puck slides on a perfectly frictionless surface, it will eventually slow down because of its inertia

false

Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to

follow a straight-line path

an object following a straight-line path at constant speed:

has zero acceleration

which of the following terms represents an object's resistance to change motion?

inertia or mass

the amount of matter in an object is called its

mass

the units of force can be in

pounds or newtons

As an object freely falls downward, its

velocity increases

If you were an astronaut in space and you threw a wrench, the amount of force needed to keep it going would be:

zero