8th 1.3

If you are wearing roller skates and you push against a wall, you roll backwards. Why?

• The wall is bigger than you are, so it pushes you with a greater force than you push it.
• Every action has an equal and opposite reaction.
• There is no friction between your roller skates and the floor
• You and the wall have opposite charges, so the wall repels you.

A waterfall is an example of:

• energy being destroyed.
• energy being created.
• kinetic energy being converted into potential energy.
• potential energy being converted into kinetic energy

When one figure skater pushes on another, both skaters move in opposite directions. Which of Newton's laws of motion best explains why this occurs?

• Newton's First Law
• Newton's Second Law
• Newton's Third Law
• Newton's Fourth Law

Newton's third law of motion states that _____.

• for every action, there is an equal and opposite reaction
• an object at rest will stay at rest or an object in motion will stay in motion with a constant velocity.
• acceleration is directly proportional to the magnitude of the force acting on it and inversely proportional to the mass of the object
• whenever an object is falling, gravity pulls it down.

Which of these terms refers to energy waiting to be released?

• kinetic
• gravitational
• potential
• total

If you throw a ball into the air, where will it have the greatest gravitational potential energy?

• on the way up
• on the way down
• at its highest point
• when you catch it

When the bowstring of a bow is pulled back, ready to shoot an arrow, the bowstring has -

• gravitational potential energy

• elastic potential energy

• potential energy

• kinetic energy

Which of the following is an example of potential energy?

• a rolling ball

• a turning windmill

• a compressed spring

• a moving train

According to Newton's third law, which statement describes why it is difficult to walk on icy pond?

• Your shoes push against the ice, but the ice cannot push your shoes

• Extremely low friction between your shoes and ice eliminates traction to move you forward

• The ice is cold so it crumbles as you push against it.

• The ice melts under your shoes, making it much more slippery.

Force equals mass x ______.

• velocity
• acceleration
• speed
• distance