Linear Momentum AP Physics Chapter 7

Linear Momentum 7.1 Momentum and Its Relation to Force

Linear momentum – product of an objects mass and its velocity Unit is a kgm/s The quantity is only useful when discussing collisions 7-1

7.1 Momentum and Its Relation to Force Impulse 7-1

7.1 Momentum and Its Relation to Force Impulse 7-1

7.1 Momentum and Its Relation to Force Impulse Or 7-1

7.1 Momentum and Its Relation to Force In a collision, to decrease force, we increase time of the collision Air Bags 7-1 Consumer Report

Linear Momentum 7.2 Conservation of Momentum

Two kinds of collisions 1.Perfectly elastic – objects bounce apart 2.Perfectly inelastic – objects stick together 7-2

7.2 Conservation of Momentum In reality collisions are a combination of the two. Law of Conservation of Momentum – in a closed system, momentum is conserved in a collision 7-2

7.2 Conservation of Momentum In an elastic collision Direction of velocity is given by the sign of the velocity. 7-2

7.2 Conservation of Momentum In an inelastic collision 7-2

7.2 Conservation of Momentum In an explosion The reverse of a Inelastic collision 7-2

Linear Momentum 7.3 Conservation of Momentum in Collisions

7.3 Conservation of Energy and Momentum Energy (mechanical) is conserved in an elastic collision So 7-3

7.3 Conservation of Energy and Momentum Any collision in which energy is lost, is considered inelastic. 7-3

Linear Momentum 7.4 Collisions in Two Dimensions

inelastic collisions in two dimension As always each dimension is treated independently Then use vector addition to calculate the final answer 7-4

Linear Momentum 7.5 Center if Mass

7.5 Center of Mass Even if an object rotates there is one point that moves in the same that a particle would move if subject to the same force. 7-5

7.5 Center of Mass Center of mass – the point that does not rotate Center of gravity – the point at which the force of gravity can be considered to act 7-5 Java Applet