1. Chapter 10 Section 4 Newton’s Third Law

2. Newton’s Third Law of Motion Newton’s third law of motion states that if one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object. Action reaction Pairs When you jump you push on the ground with your feet, action force. The ground pushes back on your feet with equal and opposite force. Detecting Motion when the earth’s gravity pulls on an object, you cannot detect the equal and opposite reaction of Earth Do action-reaction forces cancel? NEVER Because they are acting on different objects.

3. Momentum Momentum is a property of a moving object that depends on object’s mass and velocity. You can calculate the momentum of a moving object by multiplying the object’s mass and velocity Momentum=Mass X Velocity The more momentum a moving object has, harder it is to change its velocity.

4. Conservation of Momentum When a moving object hits another object, some or all of the momentum of the first object is transferred to the other object. Law of conservation of momentum states that momentum of any group of objects remains the same, or conserved, unless outside forces act on the object. Collision with two moving objects The momentum of the first object decreases, and the momentum of the second object increases. Collision with one moving object All of the momentum of the moving object is transferred to the other object. Collision with connected objects The momentum of both objects will be the same. (Page 398)