# Physics P2 Kinetic Energy

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- Created by: Dominic Hayward
- Created on: 14-05-13 17:05

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- Kinetic Energy
- Forces and Energy
- Work done and energy transferred are measured in joules, J.
- Work is done whenever a force moves something.
- Eg. Walking up stairs, lifting objects

- Work is done whenever a force moves something.
- Power is a measure on how quickly work is being done.
- Work done and energy transferred are measured in joules, J.
- Work is done whenever a force moves something.
- Eg. Walking up stairs, lifting objects

- Work is done whenever a force moves something.
- P=E/t (P is the power in watts, E is work done and t is time taken.

- Work done and energy transferred are measured in joules, J.
- W=F*d ( W is work done in joules, F is th eforce in newtons and d is the distance moved in the direction of the force)

- Work done and energy transferred are measured in joules, J.
- Gravitational Potential Energy
- On earth there is always the force of gravity acting on us.
- The amount of gravitiational potential energy depends on:
- Height above ground
- Mass

- If an object is lifted work is done against gravitational force so it gains energy.
- Ep=m*g*h (Ep is the change in gravitational potential energy, mis the mass, g is gravitational field strength and h is the change in height)

- Kinetic Energy
- All moving objects have kinetic energy. The amount depends on
- Speed
- Mass

- Ek=0.5*m*v^2 (Ek is the kinetic energy in joules, m is the mass in kg and v is velocity in metres per second

- All moving objects have kinetic energy. The amount depends on
- Transferring Kinetic Energy
- The pendulum is a machine that converts gravitational potential energy into kinetic energy, and vice versa.
- When the bob is at the highest point in the swing it has no kinetic energy but a maximum gravitational potential energy
- As the bob swings downward, gravitational potential energy is transferred to kinetic energy and the bob accelerates
- However some energy is transferred to heat and becomes lower at each swing

- Momentum
- A change in momentum occurswhen a force is applied to a object which can move or is moving.
- It is difficult to change the direction of a object with a lot of momentum
- P=m*v (p is the momentum in kilograms metres per second, m is mass in kilograme and v is velocity in m/s)
- Momentum depends on the direction of travel, so the momentum will change
- the object sppeds up or slows down
- the object changes direction

- Conservation of momentum means that energy can never be lost or destroyed

- Forces and Energy

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