LINEAR MOMENTUM Momentum : a vector quantity defined as the product of an object ’ s mass and velocity Momentum describes an objects motion p = mv The direction of the momentum is the direction of the velocity. The SI units are kilogram-meters per second (kg-m/s) IMPULSE A change in momentum takes force and time . Impulse : for a constant external force, the product of the force and the time over which it acts on an object. F ∆ t = ∆ p = m(vf –v0) In soccer for example : when the ball is moving very fast the player must exert a large force over a short time to change the ball ’ s momentum and quickly bring the ball to a stop. Stopping times and distances depend on the impulse-momentum theorem. A change in momentum over a longer time requires less force . AN ANALOGY A mood is something you have – you are happy, sad, angry, etc. – it is a characteristic of your current state of being . In the same way, momentum is something that an object has – it is a characteristic of its current physical state
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