# Energy – a global currency

### How to create a pendulum that will swing for the longest time?

In this exercise we attempted to build a pendulum in 15 minutes, with big height, big mass at the bottom and minimal friction in its movement.

This was pretty intuitive but when you measure it according some physics, thing start to make sense.

the Energy (in this case Kinetic) in our pendulum is measured in Joules (force over a distance) It follows the formula for Kinetic Energy: KE = ½ mv2 where m = mass (in Kg) and v = velocity (in meter/second) the result is in Joule. We are missing the velocity (change of position over time) here which we didn’t measure in this experiment. BUT we can calculate the Gravitational Potential Energy since we have mgh:

• Mass = 1.5 Kg
• Gravitational Acceleration = 9.8 but in our case since its rotational 6.28 m/s/s
• Height = 1.5 m

A couple of important formulas:

Force = Mass * Acceleration

Mass * Acceleration * Height = Potential energy

Joule (the energy) =  Neuton force (KG) * Meter (distance)

Watt power = 1 Joule energy / 1 second time

Kinetic Energy = ½ mv2