Kinetic energy and potential energy are two main types of energy that work together to show a very important idea called the Law of Conservation of Energy.

This law says that energy can’t be created or destroyed. It can only change from one form to another.

Potential Energy (PE)

• What is it? Potential energy is the energy stored in an object because of where it is or its condition.

• How do we calculate it? You can find the potential energy of an object that is a certain height using this formula:

  $PE = mgh$

  Here’s what the letters mean:

  • $m$ = mass of the object (how heavy it is, measured in kilograms),

  • $g$ = the force of gravity (which is about $9.81 \, m/s^2$, or how fast things fall),

  • $h$ = height above a starting point (measured in meters).

Kinetic Energy (KE)

• What is it? Kinetic energy is the energy of an object that is moving.

• How do we calculate it? You can find the kinetic energy of an object using this formula:

  $KE = \frac{1}{2} mv^2$

  Here’s what the letters mean:

  • $m$ = mass of the object (measured in kilograms),

  • $v$ = speed of the object (measured in meters per second).

Energy Changes

1. Example: A roller coaster is a great way to see how kinetic and potential energy work together.

   • At the highest point of the ride, the coaster has a lot of potential energy and not much kinetic energy.
   • As it goes down, the potential energy changes into kinetic energy, reaching the most kinetic energy at the bottom.

2. Numbers:

   • Imagine a coaster that is 50 m high and weighs 500 kg.
   • At the top, its potential energy would be:

   $PE = 500 \times 9.81 \times 50 = 245,250 \, J$

   • When the coaster gets to the bottom, that energy becomes kinetic energy, showing that energy stays the same at $245,250 \, J$.

In summary, the idea of energy conservation shows us how kinetic and potential energy change into one another. Even though energy can change forms, the total amount stays the same in a closed system.