Energy P5

Energy and Energy Transfers

Energy is held in Energy Stores:

• Kinetic anything moving
• Thermal  All objects have energy the hotter the object the more energy in the store
• Chemical   e.g food
• Gravitational Potential an object raised above ground level 
• Elastic Potential anything stretched  e.g like a spring or rubber band
• Electrostatic two charges that attract or repel each other
• Magnetic Two magnets that attract or repel each other
• Nuclear the nucleus of an atom releases energy from this store in nuclear reactions.

Energy can be transferred between energy stores

• By Heating 
  
• Mechanically A force does the work
• Electrically  A Moving charge does the work
• By radiation  Energy transferred by  e.g sound/light

When a system changes, energy is transferred.

A system is a single object when a system changes the energy is stored in one of the ways just discussed.  Closed systems are when no matter or energy can enter or leave. e.g a spoon in a  sealed thermos flask with hot soup. the spoon will become hot but no energy will leave the flask. The total energy stays the same.

Law Of Conservation Energy

Energy can be transferred usefully, stored or dispelled but can never be created or destroyed.

This means that when systems change energy is just moved between stores it never disappears. when it is dispelled it is wasted it is never gone it is just transferred to a energy store that we didn't want.

Forces can cause Mechanical Energy Transfer.

If a force moves an object then energy is transferred.  Energy is transferred mechanically when a force moves an object and when a force slows down or stops an object. 

e.g

A ball projected up a slope, energy transferred mechanically from the kinetic energy store of the ball to its gravitational energy store.  The ball slows down because the energy is being transferred away from its kinetic energy store.

A ball falling from a height The ball is accelerated by the constant force of gravity.  Energy is transferred mechanically from ball's gravitational potential energy to its kinetic energy store.

A car slowing down friction acts between the car breaks and the wheels energy transferred mechanically from wheels (Kinetic energy store) to the thermal energy store of the breaks and the wheels.

Energy is transferred when you heat something up.

An object is heated, energy is transferred to its thermal energy store.  This causes the temperature to increase.

E.g water…