Newton's Third Law

The nozzle of a toy rocket is pointed down so that as fuel is ignited, the exhaust pushes down. Why is this necessary?

• The rocket is protected from the heat of the exhaust.

• Burned fuel can be collected on the ground.

• As fuel is combusted, the rocket pushes the gases backward and the gases push the rocket forward.

• This allows the rocket to be steered properly.

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For every force there is an equal and opposite reaction between ___.

• Interacting objects

• Newton

• Force; same

• Friction

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True or False? A rocket launched into space and a balloon accelerating upward are both examples of Newtons Third Law.

• True

• False

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Which best explains why we are able to accelerate forward when starting to run?

• As one leg moves backward, it provides an equal and opposite force for the other foot to move forward.

• No acceleration takes place. Runners are always at a fixed velocity.

• The striking foot pushes backward against the ground. The friction with the ground provides an equal and opposite force forward.

• The runner's upper body quickly leans forward, causing the entire body to begin accelerating forward

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NGSS.MS-PS2-2

A baseball player hits a ball with 400 N of force. How much force does the ball exert on the bat?

• 300

• 400

• 500

• Not enough info to tell

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Which of Newton's Laws gives the reason for why you can feel things that you touch?

• second

• third

• first

• all of the above

When you are sitting in a chair, your body exerts a ___ on the chair and the chair exerts the ___ force back.

• Interacting objects

• Newton

• Force; same

• Friction

When applying a force to a book on a desk, the force must be greater than the force of ___ in order for the book to move.

• Interacting objects

• Newton

• Force; same

• Friction

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NGSS.MS-PS2-2

True or False? A train moving at a constant speed and a girl circling on a carousel are both examples of Newtons Third Law.

• True

• False

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How does Newton’s third law explain how a rocket takes off?

• The rocket’s acceleration is positive, while the gasses acceleration is negative but the direction is the same. 

• The rocket is at rest until ignition.

• The hot gasses move in one direction, while the rocket moves in the opposite direction but with equal force.