Physics - Roller Coasters and Relativity

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)

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.