Potential Energy Calculator

The formula this calculator uses

PE = m x g x h

PE

Gravitational potential energy stored, in joules

m

Mass of the object, in kilograms

g

Gravitational acceleration, about 9.80665 metres per second squared

h

Height above the reference point, in metres

How to check the result by hand

1. 1

   Weigh the object in kilograms

   Grams must be divided by 1000 before they go into the formula. A 500 gram ball is 0.5 kilograms, and using 500 would inflate the answer a thousandfold.

2. 2

   Measure the height from a reference point you have chosen

   Any reference works as long as both ends of the motion use the same one. A 20 metre lift measured from the ground stores the same energy as the same lift measured from a platform, provided the platform is the zero both times.

3. 3

   Multiply mass by gravity

   Ten kilograms times 9.80665 metres per second squared gives 98.0665 newtons, which is simply the object's weight. It is worth pausing here because the weight is a force and the next step turns it back into energy.

4. 4

   Multiply by the height

   98.0665 newtons times 20 metres gives 1961.33 joules. The newton-metre is the same as the joule, which is why a force multiplied by a distance produces an energy.

5. 5

   Use the height again for the fall

   If the object is released, the impact speed is the square root of two g h, here 19.80570624845274 metres per second, and the fall takes 2.0196199771025523 seconds. Both come from the same height and neither needs the mass.