Newton’s 3 Laws of Motion Sir Isaac Newton developed his famous 3 laws of motion from 1665-1666. 1st Law of Motion: An object at rest will remain at rest, an object in motion will remain in motion at a constant velocity unless acted upon by an outside force. What does this mean?? Inertia -- the property of matter that tends to resist any change in motion (it wants to keep doing what it is doing). An object with a lot of inertia takes a lot of force to start or stop.

If objects in motion tend to stay in motion, why don’t moving objects keep moving forever? Things don’t keep moving forever because there’s almost always an unbalanced force acting upon it. A book sliding across a table slows down and stops because of the force of friction. If you throw a ball upwards it will eventually slow down and fall because of the force of gravity.

2nd Law of Motion Newton’s 2nd Law of Motion states the acceleration of an object is directly proportional to the force acting on the object, and inversely proportional to the mass of the object.

One Newton (1N) = 1 kg x 1 m/sec/sec SAMPLE PROBLEM: What acceleration will result when a 12-N net force is applied to a 1-kg golf ball? A 6-kg bowling ball? Golf Ball: Bowling Ball: One Newton (1N) = 1 kg x 1 m/sec/sec ** Notice how the change in mass affects the acceleration when the force applied is the same.

SAMPLE PROBLEM: A Ford minivan has a mass of 1000 kg. A Chevy corvette has a mass of 500 kg. Both cars will accelerate at a rate of 2 m/sec/sec. Find how much force is needed from the engine to move the cars? Mini-Van: Corvette: -when mass is in kg, and acceleration is in m/sec/sec the force is in newtons (N).

Newton’s 3rd Law of Motion Newton’s 3rd Law of Motion says that when one object applies a force on a second object, the second object applies a force of the same size, but in the opposite direction, on the first object. According to Newton’s third law, the bumper cars apply forces to each other that are equal but are in opposite directions. Action and Reaction Forces When two objects apply forces on each other, one force is the action force, and the other is the reaction force. The bumper car that accelerates into the other car applies the action force. The car that takes the hit applies the reaction force.

Force Pairs As you walk around the amusement park, your shoes push against the ground. If the ground did not push back with equal force, gravity would pull you down into the ground! When two objects apply forces on each other, the two forces are a force pair.   Opposite Forces The opposite forces of the bumper cars hitting each other are a force pair. Force pairs are not the same as balanced forces. Balanced forces combine or cancel each other out because they act on the same object. Each force in a force pair acts on a different object.

Newton’s 2nd Law of Motion – Video Clips https://www.youtube.com/watch?v=iwP4heWDhvw https://www.youtube.com/watch?v=qu_P4lbmV_I