Changing the way you learn

Chapter 7. Work, energy and power

Doing work, transferring energy
1. Factors for doing work
  1. The size of the force F - bigger the force, greater work
  2. The distance travelled x - Further distance, more work
2. Work done = force x distance moved in direction of force
  1. W=Fx
  2. Work in Nm (Newton metres) or J (Joules)
  3. Work Done = Energy transferred
  4. If F at angle theta to direction of motion then W = FxCos(theta)
3. Change in GPE = Weight x Change in height
  1. Ep = mgh
4. Faster an object, greater kinetic energy
  1. Kinetic energy = 0.5 x mass x speed^2
    1. Ek = 0.5mv^2
5. If no energy is lost during energy transfer then Change in GPE = Change in KE
  1. mgh = 0.5mv^2
Energy transfers and conservation
1. Energy efficiency = (Useful output energy / Total input energy) x 100%
2. Sankey diagram can represent energy transfer
3. Conservation of energy - The total energy at the beginning = Total energy at the end in a closed system
Power
1. Power is the rate at which work is done
  1. P = W / t
  2. Power measured in Watts (W) (Joules per second)

Chapter 7. Work, energy and power

	Created by Scott Heiron over 10 years ago