The Principle of the Conservation of Energy
Energy conservation means using less fossil fuels etc.
However, the principle of the conservation of energy is a different story. Without it, life as we know it would cease to be. The principle is:
Energy can never be created nor destroyed - only converted from one form to another
It is the principle behind how we get electricity, as much electricity comes from burning fossil fuels etc -- the energy is just converted into a different form.
Gravitational potential --> kinetic energy...Also:
Energy is only useful when it's converted from one form to another
Calculating the Speed of Falling objects:
When something falls, it's potential energy is converted into kinetic energy. This means it loses potential energy and gains kinetic energy. Therefore:
potential energy lost = kinetic energy gained.
(Example is on back of card)
Kinetic Energy Example
Example: A mouldy tomato of mass 140kg is dropped from a height of 1.7m. Calculate it's speed as it hits the floor.
Answer: There are four key steps to this method.
1) Find the PE lost: PE = mgh = 0.14 x 10 x 1.7 = 2.38 J <-- This is also the KE gained/
2) Equate the number of joules of KE gained to the KE formula with v in:
3) Stick the numbers in
4) You have your answer.
When dealing with roller coasters or falling objects, remember that speed is not distance x time. The first step is finding the PE lost.