# Momentum, Energy and Work

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• Work, Momentum and Energy
• Equations
• Work=Force applied x Distance
• Force = newtons
• Work = Joules
• Distance = metres
• Weight = Gravitational field strength x mass
• GFS = 10N on earth
• Change in gravitational potential energy = mass x GFS x height
• Power = Energy÷time
• Kinetic energy = 1/2 x mass x velocity
• Momentum = mass x velcoity
• M1V1 = M2V2
• Gravitational potential energy is the energy from how high you are.
• Mass is the amount of stuff inside you
• Momentum is the measure of how much momentum there is in an object
• During a collision, the law of conservation of momentum applies in a closed system - the total momentum before an event is equal to the total momentum after the event
• For example: an 80kg rugby player ran at a velocity of 5m/s.... an 800kg car moves with the same momentum as the rugby player. Calculate the velocity of the car when the momentum of the rugby player moves at 400kgm/s: 800kg x velocity = 400kgm/s... velocity = 400/800 = 0.5m/s
• Impact Forces
• if you increase the amount of time involved in the collision then there is more time for the force to be dissipated out of the collision = less injuries
• Decelleration = change in velocity / time