Newton's Laws and Free Body Diagrams

What is inertia?

• the force that opposes motion

• the force of attraction between 2 objects

• an object's tendency to stay in its state of motion

• a change in an object's speed and/or direction

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Which of the objects listed below have the greatest inertia?

• A 700 kg object that is not moving.

• A 300 kg object that is not moving on the Moon.

• A 250 kg object moving at 6 m/s.

• A 500 kg object moving at 3 m/s.

While you’re ice-skating with your friends, you push off from one end of the rink and slide forward. Based on Newton’s first law of motion, what is true?

• You will lose your balance and fall over before you reach the middle of the ice rink.

• You will continue to slide across the ice until a force makes you stop or change direction.

• The force of gravity will make you keep your velocity until your friend makes you stop.

• The size of your ice skates will determine how quickly or slowly you travel across the ice.

A skateboard rolls down a hill, reaches the level surface and eventually comes to a stop. The fact that the skateboard ultimately stops is best explained by ____.

• an unbalanced force would be required to keep the sled moving forward at constant speed

• the presence of an unbalanced force (e.g., friction) can cause a moving object to stop

• the presence of inertia causes it to stop

• the natural tendency of any object is to ultimately stop

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An ice skater pushes off a wall and glides backwards for a few meters and then stops.

Which statement best describes an action-reaction force pair in this statement?

• The friction of the ice decreases as the blade of the skate moves on the ice.

• The wall pushes on the skater as the skater pushes on the wall.

• The ice skates slow down, and the skater stops

• The skaters exerts a force on the wall, and blade exerts a force on the ice.

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A semi truck and a Volkswagen (small car) traveling at the same speed have a head on collision. Which statement is correct?

• The impact force is greater on the Volkswagen.

• The impact force is greater on the semi truck.

• The acceleration is less for the Volkswagen.

• The acceleration is less for the semi truck.

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A soccer ball breaks through a window. How does the force on the window compare with the force on the ball?

• The ball experiences a greater force

• The window experiences a greater force

• The window and ball experiences forces equal in magnitude

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The moon orbits the Earth. Which is true about the motion of the moon?

• Forces acting on the moon are balanced since it is remaining at a constant speed.

• Forces acting on the moon are balanced since its state of motion is not changing

• Forces acting on the moon are unbalanced since it is constantly changing direction

• Forces acting on the moon are unbalanced since the force acting on it constantly changes

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The hockey puck is moving at a constant velocity across the ice and no player is moving it. What forces does the puck experience at this moment?

• Gravity

• Gravity and Normal

• Gravity, Normal, and Friction

• A ghost is pushing it

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A person is attracted towards the center of Earth by a 440N gravitational force. The force with which Earth is attracted toward the person is

• More than 440N

• Less than 440N.

• The same, 440N.

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