# Work, Energy Momentum

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• Created by: Fiona S
• Created on: 13-03-15 20:07
• Work, Energy, Momentum
• Gravitational Potential Energy
• Energy an object as due to its position.
• Ep=m x g x h
• Kinetic Energy
• Energy an object has due to its movement
• Ek=1/2 x m x v^2
• Ek is proportional is v^2
• Momentum(P)
• Momentum is the product of an objects mass and velocity.
• P = m x v
• P=(kgm/s)         m=(kg)       v =(m/s)
• Conservation of Energy
• Energy cannot be created or destroyed, it can only be transferred
• Falling objects transfer Ep to Ek.
• Neglecting air resistance.
• Conservation of Momentum
• In a closed system the total momentum before an event is equal to the total momentum after an event.
• Assign +ve and -ve directions.
• Event = Collision or Explosion
• Power
• Power is the rate at which work is done
• P = WD/t
• P = W            WD = J        t = s
• Impact Force
• To decrease the impact force we must increase the impact time
• F=Change in P/t
• Work Done
• Work is done when a force acts on an object over a certain distance
• WD=Force x Distance
• WD = Joules  F= Newtons  D= Meters
• Distance must be in the same direction as the force
• Work done is equivalent to energy transfer