MOMEMTUM MOMENTUM Momentum Momentum is a property of

MOMEMTUM MOMENTUM 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.

MOMEMTUM MOMENTUM Momentum § The momentum of a ball depends on its mass and velocity. § Ball B has more momentum than ball A.

MOMEMTUM MOMENTUM 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)

MOMEMTUM MOMENTUM 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.

MOMEMTUM MOMENTUM Momentum § § Ball A is 1 kg moving 1 m/sec, ball B is 1 kg 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.

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

MOMEMTUM MOMENTUM 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. 1. 2. 3. 4. 5. 4 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.

MOMEMTUM MOMENTUM 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.

MOMEMTUM MOMENTUM Conservation of Momentum

MOMEMTUM MOMENTUM 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.

MOMENTUM 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