Newton's Law

What is Newton's First Law

• F=ma

• Every action has an equal and opposite reaction

• An object at rest stays at rest, an object in motion stays in motion. 

• Friction 

The law of inertia (Newton’s First Law) applies

• to both moving and nonmoving objects

• only to moving objects

• only to objects that are not moving

Why is the net force 0 in the image?

• Because the elephants are the same size

• Because they are both pulling the same amount of force in opposite directions

• Because they are elephants

• Because they are pulling away from each other.

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According to Newton’s first law of motion, a moving object that is not acted on by an unbalanced force will

• remain in motion.

• eventually come to a stop.

• change its momentum.

• accelerate.

A car moves at a constant speed without changing direction. What HAS to be true about the forces on the car?

• A force is pushing the car in the direction it's moving.

• The forces on the car are not balanced.

• The forces on the car are balanced.

• Forces push on the car in all directions.

Answer explanation

The car isn't changing speed or direction, so the forces have to be balanced!

A ball is sitting still on a plate. How could the ball start moving?

• The ball's inertia disppears.

• All the forces on the ball stop.

• A new, balanced force acts on the ball.

• A new, unbalanced force acts on the ball.

• A

Answer explanation

To cause a change in motion, a force must be unbalanced (greater in one direction than in others.)

A car turns left suddenly. The drink in the drink holder falls over onto the person sitting in the right-hand seat. Why?

• The car turns left, but the drink continues going straight, tipping it to the right.

• The car turns left, and the drink is pushed in the opposite direction.

• The car turns left, and the force causes the drink to move. It could have fallen either way.

• The force of the turn pushes both the car and drink to the left, but the drink isn't pushed as much.

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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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Why does an 18-wheeler truck have more inertia than a bicycle?

• it has more mass

• it has more volume

• it is not as aerodynamic

• It has more space

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Which of the following is an example of inertia?

• Slamming on the breaks in your car and flying forward.

• An apple falling off of a tree. 

• Running at a cross country event. 

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