AQA GCSE HIGHER PHYSICS - Calculating Gravitational Potential Energy

AQA GCSE Higher Physics: Calculating Gravitational Potential Energy

Gravitational potential energy (GPE) is the energy an object possesses due to its position in a gravitational field. It is calculated using the following formula:

GPE = mgh

Where:

• GPE is the gravitational potential energy in joules (J)
• m is the mass of the object in kilograms (kg)
• g is the acceleration due to gravity (approximately 9.8 m/s²)
• h is the height of the object above a reference point (usually the ground) in meters (m)

Example:

A 2 kg book is lifted 1.5 meters above the ground. Calculate its gravitational potential energy.

Solution:

1. Identify the known values:

   • m = 2 kg
   • g = 9.8 m/s²
   • h = 1.5 m

2. Substitute these values into the formula:

   • GPE = (2 kg) × (9.8 m/s²) × (1.5 m)

3. Calculate the result:

   • GPE = 29.4 J

Therefore, the book has a gravitational potential energy of 29.4 joules.

Key Points:

• Gravitational potential energy is a scalar quantity, meaning it has magnitude but no direction.
• The reference point for calculating GPE can be chosen arbitrarily. However, it is important to be consistent with the reference point throughout the calculation.
• The higher an object is above the reference point, the greater its GPE.

Practice Problems:

1. A 50 kg person climbs a 10-meter ladder. What is their GPE at the top of the ladder?
2. A 0.5 kg ball is thrown vertically upwards to a height of 5 meters. What is its GPE at its highest point?

Answers:

1. GPE = 4900 J
2. GPE = 24.5 J

Additional Notes:

• The concept of GPE is closely related to the work-energy theorem, which states that the work done on an object is equal to the change in its kinetic energy.
• When an object falls, its GPE is converted into kinetic energy.
• The formula for GPE can be rearranged to solve for mass, height, or acceleration due to gravity.

By understanding the concept of gravitational potential energy and its formula, you can solve a variety of problems related to energy and motion in AQA GCSE Higher Physics.