P1.1 and P1.2 Changes in Energy Stores + Conservat
P1.1
Energy can be stored in a variety of different energy stores
Energy is transferred by heating, by waves, by an electric current, or by a force when it moves an object
When an object falls and gains speed, its store of GPE decreases and its kinetic energy store increases.
When a falling object hits the ground without bouncing back, it's kinetic energy store decreases. Some or all of its energy is transferred t the surroundings - the thermal energy store of the surroundings increases, and energy is also transferred by soundwaves.
P1.2
Energy cannot be created or destroyed.
Conservation of energy applies to all energy changes.
A closed system is a system whch no energy transfers take place out of or into the energy stores of the system
Energy can be transferred between energy stores within a closed system. The total energy of the system is always the same, before and after, any such transfers.
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P1.3 and P1.4 Energy and Work + GPE stores
P1.3
Work is done on an object when a force makes the object move.
Energy Transferred = Work Done
Work done, W (joules, J) = Force applied, F (newtons, N) x distance moved along the line of action of the force, s (metres, m)
Work done to overcome friction is transferred as energy to the thermal energy stores of the objects that rub together and to the surroundings.
P1.4
The GPE store of an object increases when it moves up and decreases when it moves down.
The gravitational potential energy store of an object increases when it is lifted up because work is done on it to overcome the gravitational force.
The gravitational field strength on the moon is less than on the earth.
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P1.5 Kinetic energy + elastic energy stores
P1.5
The energy in the kinetic energy store of a moving object depends on its mass and its speed.
The kinetic energy store of an object is Kinetic Energy = 1/2 x mass x speed^2
Elastic Potential energy is the energy stored in an elastic object when work is done on the object.
The elastic potential energy stored in a stretched spring is Elastic Potential energy = 1/2 x spring constant x extension^2
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