Motion

A metal ball is put into the end of the tube indicated by the arrow. The ball is then shot out of the other end of the tube at high speed. Pick the path the ball will follow after it exits the tube. Note - you are looking down on these tubes, they are not vertical.

Either B or D because they both curve the a small amount like the tube did

Describe its motion relative to the wagon.

It will stay in the back of the wagon unless you stop or go down a hill.

If an elephant were chasing you, its enormous mass would be most threatening. But if you zigzagged, its mass would be to your advantage. Why?

It would take a lot of force and time to go back and forth.

If you were in a spaceship and fired a cannonball into space, how much force would have to be exerted on the ball to keep it moving once it has left the spaceship?

None because there is no gravity in space, it's just nothing.

How much does an astronaut weigh out in space, far from any planets?

Nothing because there is nothing weighing down on him.

Suppose you place a ball in the middle of a wagon, and then accelerate the wagon forward. Describe the motion of the ball relative to the ground.

The ball will go backward because it wants to stay in place but the wagon is going forward.

inertia

The force that keeps an object in motion or at rest.

Many automobile passengers have suffered neck injuries when struck by cars from behind. How does Newton's law of inertia apply here?

Their bodies slam forward but their seatbelts keep them in place and it puts the force of the crash and the weight of your head on your neck.

How do headrests help to guard against this type of injury?

They keep your head from going back while being pushed and then forwards, it just makes it forward.

If suddenly the force of gravity of the sun stopped acting on the planets, in what kind of path would the planets move?

They would be like the marble on the plate when the wedge is removed.

Two closed containers look the same, but one is packed with lead and the other with a few feathers. How could you determine which has more mass if you and the containers were orbiting in a weightless condition in outer space?

You couldn't unless you brought it into the pressurized area of your ship.

An object's motion will not change as long as the net force acting on it is ...

constant

Objects with greater mass have ... inertia.

greater

If an object is not moving, ... will cause it to remain stationary.

inertia

Newton's first law of motion is also called the law of

inertia

Once objects start moving, ... keeps them moving.

inertia

When the car you are riding in stops suddenly, you move forward because of

inertia

weight

the amount of gravity pulling down on an object.

mass

the amount of matter in an object

gravity

the force of an large mass pulling an object down towards the other object.

friction

the force that works against inertia and wants to make an object stop.

An object at rest will stay at rest unless a(n) ... force acts on it.

unbalanced