Work, Energy and Momentum
- Created by: SerinaHussain
- Created on: 06-04-14 11:05
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- Work, Energy and Momentum
- Energy and Work
- When work is done, the supplied energy is transferred to the object so the work done is equal to the energy transferred
- W=F X D
- Work done s measured in Joules
- The work done to overcome friction is transferred into energy by heating
- Gravitational Potential Energy
- Energy stored in an object due to its position on Earth's gravitational field
- Ep=m x g x h
- Power is the rate of transfer energy
- P= E/T
- Power- Watts (W)
- Kinetic Energy
- The greater the mass the faster the speed of the object- the more kinetic energy it has
- Energy in elastic once being stretched is called Elastic Potential Energy
- When the elastic returns to its original shape the energy is released
- Momentum
- All moving objects have momentum
- The greater the mass the greater velocity of an object- the greater its momentum
- p= m x v
- Law of conservation of Momentum
- The total change in momentum is zero
- The total momentum before is equal to the total momentum after
- Explosions
- In and explosion the objects move apart with equal and opposite momentum
- One direction must be defined as positive and the opposite must be defined negative
- So the total momentum after the explosion is zero
- In and explosion the objects move apart with equal and opposite momentum
- Impact forces
- When a force acts on a moving object, its momentum changes
- The longer the time taken for change in momentum, the smaller the force then acts
- If the impact time is short, the force is large. As impact time increases the forces become less
- Crumple zones- e.g. cars folding in on themselves increases the impact time so reduces the force on the car
- Energy and Work
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