Newton's First Law

According to Newton's First Law, what is needed to cause an object to change speed or direction?

• A balanced force

• An unbalanced force

• Nothing, it will change without force

What is acceleration?

• When something changes direction

• When something changes speed

• Either of these

An astronaut drifting in space will continue drifting forever unless they use a force to change their direction or speed

• True

• False

Why will the astronaut continue drifting forever?

• They have a strong weight force in space

• There are only magnetic forces acting in space

• There are no friction or other forces acting in space

On earth, a car rolling on the road without the engine running will slowly roll to a stop. Why?

• Because Newton's First Law is wrong

• Because there is an unbalanced force caused by friction

• Because the forces are balanced

A car on a slippery surface, like ice, has trouble changing speed or direction because...

• There isn't enough friction to allow the car to change speed or direction

• There is too much friction so the car can't change speed or direction

If a car comes to a stop, the things inside it will...

• Stop as well, without needing anything to help

• Keep moving, until there is an unbalanced force to stop them

A falling object, like a ball, will accelerate (speed up)

• True, until it reaches terminal velocity

• True, and it will accelerate forever

• False, it will fall at constant speed

The weight force on a falling object, like a ball, is unbalanced

• True, although the friction force on it gets bigger as it falls faster until the forces become balanced

• True, and they are always unbalanced

• False, the weight force is always equal and opposite to the friction force

Seatbelts are a good safety device because they...

• Stop people in the back from being able to hit each other

• Provide an unbalanced force to stop people if the car stops suddenly