Newton’s 3rd Law

When your arms push against the water as you swim...

• The water pushes back

• The water pulls you in

• Nothing happens

• We need more information.

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What is Newton’s 3rd law?

• For every action there is an equal and opposite reaction

• Inertia

• Force

• Force is proportional to acceleration.

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A baseball bat hits a baseball with a force of 100 Newtons. What is the force and its direction exerted by the ball on the bat?

• 100 Newtons, same direction

• 100 Newtons, opposite direction

• 200 Newtons, opposite direction

• 200 Newtons, same direction

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The nozzle of a rocket is pointed downward so that as fuel is ignited, the exhaust pushes downward. Why is this arrangement necessary for a rocket to function properly?

• 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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Newton’s law states that for every action, there is an ________ reaction.

• unequal and opposite

• equal and similar

• stronger and opposite

• equal and opposite

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When a cannon fires a cannonball we observe Newton's third law. Which is the reaction force?

• The cannon moving forward

• The cannon moving backwards

• The cannonball moving backwards

• The cannonball moving forward

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How is this an example of Newton’s Third law?

• Only the ball is using the head

• They are both exerting an equal force on each other

• Only the head is pushing the ball

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Force always come in________

• waves

• triplets

• pairs

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A person steps out of the boat and onto the dock.  As the person moves forward onto the dock, the boat moves backward.  Which statement best describes the backward motion of the boat as the person steps forward?

• For every action there is an equal and opposite reaction.
• Every mass exerts a force on every other mass.
• An object at rest tends to stay at rest.
• Friction opposes the motion of an object.

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If the person is pushing backwards with the paddle, why do they move forward?

• The person will actually move backwards, they need to paddle the other way

• The water pushes back with an equal and opposite force

• The person is pushing harder than the water

• The water pushes back with a greater force than the person

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