Momentum  Momentum is a property of moving matter.  Momentum describes the tendency of objects to keep going in the same direction with the same speed.  Changes in momentum result from forces or create forces. MOMEMTUMMOMENTUM

Momentum  The momentum of a ball depends on its mass and velocity.  Ball B has more momentum than ball A. MOMEMTUMMOMENTUM

Momentum vs. Inertia  Inertia is another property of mass that resists changes in velocity; however, inertia depends only on mass.  Inertia is a scalar quantity. ( 10 kg)  Momentum is a property of moving mass that resists changes in a moving object’s velocity.  Momentum is a vector quantity. (10 kg x m/s east) MOMEMTUMMOMENTUM

Kinetic Energy and Momentum  Kinetic energy and momentum are different quantities, even though both depend on mass and speed.  Kinetic energy is a scalar quantity.  Momentum is a vector, so it always depends on direction. Two balls with the same mass and speed have the same kinetic energy but opposite momentum. MOMEMTUMMOMENTUM

Momentum  Ball A is 1 kg moving 1m/sec, ball B is 1kg at 3 m/sec.  A 1 N force is applied to deflect the motion of each ball.  What happens?  Does the force deflect both balls equally?  Ball B deflects much less than ball A when the same force is applied because ball B had a greater initial momentum. MOMEMTUMMOMENTUM

Calculating Momentum  The momentum of a moving object is its mass multiplied by its velocity.  That means momentum increases with both mass and velocity. Velocity (m/sec) Mass (kg) Momentum (kg m/sec) p = m v MOMEMTUM

 You are asked for momentum.  You are given masses and velocities.  Use: p = m v  Solve for car: p = (1,300 kg) (13.5 m/s) = 17,550 kg m/s  Solve for cycle: p = (350 kg) (30 m/s) = 10,500 kg m/s  The car has more momentum even though it is going much slower. Comparing momentum A car is traveling at a velocity of 13.5 m/sec (30 mph) north on a straight road. The mass of the car is 1,300 kg. A motorcycle passes the car at a speed of 30 m/sec (67 mph). The motorcycle (with rider) has a mass of 350 kg. Calculate and compare the momentum of the car and motorcycle. MOMEMTUMMOMENTUM

Conservation of Momentum  The law of conservation of momentum states when a system of interacting objects is not influenced by outside forces (like friction), the total momentum of the system cannot change. If you throw a rock forward from a skateboard, you will move backward in response. MOMEMTUMMOMENTUM

Conservation of Momentum MOMEMTUMMOMENTUM

Collisions in One Dimension  A collision occurs when two or more objects hit each other.  During a collision, momentum is transferred from one object to another.  Collisions can be elastic or inelastic. MOMEMTUMMOMENTUM

Calculating Conserved Momentum  Remember p=mv  So if it is conserved, then… m 1 v 1 =m 2 v 2  Before and after all collisions  Let’s try…. MOMENTUM