Momentum 28/12/2018 Any object that has both mass and velocity has MOMENTUM. Momentum (symbol “p”) is simply given by the formula: P V M Momentum = Mass x Velocity (in kgm/s) (in kg) (in m/s) What is the momentum of the following? A 1kg football travelling at 10m/s A 1000kg Ford Capri travelling at 30m/s A 20g pen being thrown across the room at 5m/s A 70kg bungi-jumper falling at 40m/s

Conservation of Momentum 28/12/2018 In any collision or explosion momentum is conserved (provided that there are no external forces have an effect). Example question: Two cars are racing around Teville Gate. Car A collides with the back of car B and the cars stick together. What speed do they move at after the collision? Speed = 50m/s Speed = 20m/s Mass = 1000kg Mass = 800kg Speed = ??m/s Mass = 1800kg Momentum before = momentum after… …so 1000 x 50 + 800 x 20 = 1800 x V… …V = 36.7m/s

More questions… 28/12/2018 A white snooker ball moving at 5m/s strikes a red ball and pots it. Both balls have the same mass. If the white ball continued in the same direction at 2m/s what was the velocity of the red ball? A car of mass 1000kg heading up the M1 at 50m/s collides with a stationary truck of mass 8000kg and sticks to it. What velocity does the wreckage move forward at? A defender running away from a goalkeeper at 5m/s is hit in the back of his head by the goal kick. The ball stops dead and the player’s speed increases to 5.5m/s. If the ball had a mass of 500g and the player had a mass of 70kg how fast was the ball moving? A gun has a recoil speed of 2m/s when firing. If the gun has a mass of 2kg and the bullet has a mass of 10g what speed does the bullet come out at? (Hint: total momentum before is zero and the gun has a negative velocity afterwards)

Two lorries are travelling in the same direction along a motorway. A past exam question… 28/12/2018 June 2000 Two lorries are travelling in the same direction along a motorway. Lorry A Mass = 20,000kg Speed = 14m/s Lorry B Mass = 30,000kg Speed = 20m/s Calculate the momentum of Lorry A as it travels along the motorway. Calculate the momentum of Lorry B as it travels along the motorway. (3 marks) Lorry B collides with Lorry A and they stick together. Calculate the common speed of the lorries immediately after the collision.