What is Gravitational Potential Energy?

Gravitational potential energy (GPE) is the energy stored in objects when they're lifted above the Earth's surface. Think of it as nature's battery - the higher something is, the more energy it's storing up.

A bungee jumper perfectly demonstrates this concept. At the top of the platform, they're packed with GPE. As they fall, this stored energy converts into movement energy, making them speed up.

The GPE formula is straightforward: GPE = mass × gravitational field strength × height. On Earth, we use g = 10 m/s² $sometimes 9.8 m/s²$ as our gravitational field strength.

Quick Tip: Remember that GPE depends on three things - how heavy the object is, how high it is, and which planet you're on!

Calculating GPE - Worked Example

Let's work through a proper calculation using a 12 kg dog at a height of 3.4 km (that's 3400 metres).

Using our formula: GPE = mgh

• m = 12 kg (mass of dog)
• g = 9.8 m/s² (gravitational field strength)
• h = 3400 m (height)

GPE = 12 × 9.8 × 3400 = 399,840 J

Remember: Always convert kilometres to metres in your calculations - it's a common exam mistake to forget this step!

GPE to Kinetic Energy Conversion

This is where physics gets exciting! Energy conversion between GPE and kinetic energy (KE) explains how roller coasters work without needing engines on every hill.

Picture a 1000 kg car on a roller coaster. At the top (45 m high), it has maximum GPE but zero KE because it's stationary. As it rolls down, GPE converts to KE, making the car speed up.

At the bottom, all that stored energy becomes movement energy - maximum KE and zero GPE. The car then has enough energy to climb the next hill, converting KE back to GPE.

This energy transfer continues throughout the ride, assuming no energy is lost to friction, heat, or sound.

Physics in Action: Next time you're on a roller coaster, you'll know exactly why the first hill is always the tallest - it needs to give enough GPE to power the entire ride!