Linear Momentum Linear Momentum (p) Product of mass and velocity Equation p = mv Vector quantity with direction the same as v Unit kg-m/s Relationship with Inertia More momentum something has, the harder it is to change its inertia Greater effect it will have if in an impact or collision A force is required to change an object’s momentum (increase it, decrease it, or change it’s direction) Newton’s 2nd Law Rate of change of momentum of a body is equal to the net force applied to it more force,faster momentum changed F = ma a = Δv/t F = m(v2 – v1) / t F = p 2 – p1 / t F = Δp / t Example 1 For a top player, a tennis ball may leave the racket on the serve with a speed of 55 m/s. If the ball has a mass of 0.060kg and is in contact with the racket for 4 ms, what is the force on the ball? Example 2 Water leaves a hose at a rate of 1.5kg/s with a speed of 20m/s and is aimed at the side of a car, which stops it. What force is exerted by the water on the car? Example 3 If the water splashes back from the car at 15m/s, what is the force on the car?