Newton's 3rd law

The definition of momentum is

• Mass in Motion
• The size of an object
• The velocity of an object
• A comparison between two objects

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

Tags

NGSS.MS-PS2-1

When a large truck pushes a small car with a given force, the small car is applying an equal and opposite force on the truck.

• True
• False

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NGSS.MS-PS2-1

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

• The cannon moving forward
• The cannonball moving forward
• The cannon moving backward
• The cannonball moving backward

Tags

NGSS.MS-PS2-1

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.

Tags

NGSS.MS-PS2-1

Newton's third law states that any action will have a(n) _______ and ______ reaction

• Equal and similar
• Equal and opposite
• Equal and different
• Greater and opposite

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NGSS.MS-PS2-1

A book rests on a table.  The force of gravity pulls down on the book with a force of 20 newtons. What prevents the books from accelerating downward at 9.8 m/sec²    

• The table presses back up on the book with an equal and opposite force of 20 newtons.
• The table presses back up on the book with a force greater than 20 newtons.
• The table and the book together are accelerating downwards at  9.8 m/sec²
• The inertia of the book holds it up

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NGSS.MS-PS2-4

You hit a wall with a stick.  The equal but opposite reaction is _____

• the wall pushes against you
• the stick pushes against you
• you push against the stick
• the wall pushes against the stick

Tags

NGSS.MS-PS2-1

Jenny and Johnny each have a mass of 55.0 Kg.  If both are on roller skates, and Jenny pushes Johnny, who experiences the greatest force?

• Jenny
• Johnny
• The forces are the same.

Tags

NGSS.MS-PS2-1

Jenny and Johnny each have a mass of 55.0 Kg.  If both are on roller skates, and Jenny pushes Johnny, who experiences the greatest acceleration?

• Jenny
• Johnny
• The accelerations are the same since they have the same mass and the same force is applied.