Newton's First Law: An object sitting still needs a force to get it moving. A moving object needs a force to change its direction, slow it down, or make it stop. Newton's First Law on a Rollercoaster: When the ride starts you feel like you're being pushed to the back of the seat. That's because your body is at rest when the roller coaster car moves forward. Your body wants to stay at rest, but the car's seat moves into you. When the ride stops, you feel the safety bar pushing against your stomach. That's because the car comes to a stop, but your body wants to keep moving. The safety bar keeps you from flying out of the car.
Newton's Second Law: The amount of acceleration that a force can produce depends on the mass of the object. Newton's Second Law in Juggling: It is easier to juggle tennis balls than bowling balls. That's because a bowling ball has more mass (or matter) in it than a tennis ball. The more mass, the heavier something is.
Newton's Third Law: For every action there is an equal and opposite reaction. Newton's Third Law in the Pool: As you swim, you pull your arms through the water. This motion causes the water to push back as you move forward.