Net Force and Newton's Laws

Which statement best explains Newton's Third Law of Motion?

• An object at rest tends to stay at rest.
• For every action there is an equal and opposite reaction.
• The acceleration of an object is based on the force applied.
• An object continues its motion until an unbalanced force is applied.

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Which is the best example of Newton's First Law of Motion?

• a basketball thrown in the air falls to the ground
• a soccer ball remains motionless until it is kicked by a player
• a baseball player swings at an approaching ball
• an ice skater pushes back from a wall and moves backwards

An object is resting motionless on a surface. According to Newton's 1st Law, the object will only start to move if

• the net forces on the object equal zero
• an unbalanced force is applied to the object
• the upward force of the object is equal to its acceleration
• two forces that are equal and opposite are applied to the object

As the wheels of a train push down on the track, the track pushes back against the wheels. Which of Newton's laws is used to explain these forces.

• An object at rest tends to stay at rest unless acted upon by an unbalanced force.
• The net force of an object is its mass times its acceleration.
• For every action, there is an equal and opposite reaction.
• Any 2 objects exert a gravitational force of attraction on each other.

Which example best explains Newton's Third Law of Motion?

• When a glass slid across a table, it spilled water when it stopped suddenly.
• An engine used less work to move a lighter car than when it moved a heavier car.
• When you sit on a chair, your body exerts a downward force on the surface of the chair, while the chair exerts an equal and upward force on your body. 

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A truck that is travelling at a constant speed is carrying some boxes.  If the truck comes to a sudden stop, what will most likely happen to the boxes?

• They will stay in the middle of the truck.
• They will slide toward the front of the truck.
• They will slide toward the back of the truck.
• They will fall off the side of the truck.

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A student throws a ball against a wall.  Which statement best explains what is happening in the picture.

• The energy of the ball is destroyed as it strikes the wall.
• The energy of the ball becomes negative as it hits the wall.
• The force from the wall on the ball is equal and opposite to the force from the ball on the wall.
• The force exerted by the ball on the wall is greater than the force exerted by the wall on the ball.

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Object X has twice the mass of Object Y.  Both objects are accelerating at the same rate.  Which statement best describes the motions of Object X and Object Y.

• Object X is travelling at twice the speed as Object Y.
• Object X is travelling at half the speed as Object Y.
• Object X requires twice the force to accelerate at the same rate as Object Y.
• Object X requires half the force to accelerate at the same rate as Object Y.

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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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The force that draws all objects towards Earth.

• friction
• gravity
• mass
• acceleration

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