NEWTON'S LAWS

NEWTON'S FIRST LAW

• An object at rest remains at rest, and and an object in motion remains in motion at a constant speed and in a straight line unless acted on by an unbalanced force.

EXAMPLE 1

• This explains Newton's first law because of you leave a cup on top of the car, it will fall. After it is left on the top of the car, the driver will speed away. The cup will want to stay at rest. The cup will then start to slide. As a result, it will fall off the back of the car.

EXAMPLE 2

• This explains Newton's first law because when a car is moving and suddenly stops, the passengers move forward. This happens because the car was moving forward and so was your body. As a result, your body still thinks you are still moving forward. Your body is moving forward, but the car is going in a different direction. So, you move forward suddenly.

NEWTON'S SECOND LAW

• The acceleration of an object depends on the mass of the object and the amount of force applied.

EXAMPLE 1

• This explains Newton's second law because the skater is applying force to move the skateboard. The mass of the skateboard is little. So, it requires less force for the skateboard to accelerate. The more force the skater applies, the faster the skateboard accelerates.

EXAMPLE 2

• This explains Newton's second law because the person will apply force to hit the pool ball, for it to move. The person will apply force to the stick, which will hit the ball and cause it to accelerate. How fast the ball will accelerate will depend on the force it received. The larger the force, the more the ball will accelerate.

NEWTON'S THIRD LAW

• Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.

EXAMPLE 1

• This explains Newton's third law because when a bird flies, it pushes air down. While the bird is flapping its wings, the air is pushed downward. Then the bird starts moving. As a result, the bird starts to fly. The action is the bird flapping its wings. The reaction is the bird moving and flying.

EXAMPLE 2

• This explains Newton's third law because the action is the hammer hitting the nail. The reaction is the nail going in deeper. The hammer is exerting a force on the nail. As a result the nail, exerts an equal amount of force towards the hammer. The force that the nail exerts is in the opposite direction.