AQA GCSE HIGHER PHYSICS - Weight, Mass, and Gravitational Field Strength

AQA GCSE Higher Physics: Weight, Mass, and Gravitational Field Strength

Understanding Weight and Mass

• Mass is a measure of the amount of matter an object contains. It's a fundamental property of an object and remains constant regardless of location. We measure mass in kilograms (kg).
• Weight is the force of gravity acting on an object's mass. It's a force, so we measure it in Newtons (N). Weight is dependent on the gravitational field strength.

Gravitational Field Strength

• The gravitational field strength is a measure of the gravitational force acting on a 1 kg mass at a particular location. We measure it in Newtons per kilogram (N/kg).
• On Earth, the average gravitational field strength is approximately 9.8 N/kg.

The Relationship between Weight, Mass, and Gravitational Field Strength

The relationship between weight, mass, and gravitational field strength is expressed by the following formula:

Weight = Mass * Gravitational Field Strength 

Let's break down the formula:

• Weight (W): This is the force of gravity acting on the object.
• Mass (m): This is the amount of matter in the object.
• Gravitational Field Strength (g): This is the strength of the gravitational field at the object's location.

Example:

A 50 kg person stands on Earth. Calculate their weight.

Solution:

• Mass (m) = 50 kg
• Gravitational Field Strength (g) = 9.8 N/kg
• Weight (W) = m * g = 50 kg * 9.8 N/kg = 490 N

Therefore, the person's weight on Earth is 490 N.

Important Points to Remember:

• The gravitational field strength is not constant everywhere on Earth. It varies slightly depending on altitude and location.
• On other planets, the gravitational field strength is different from Earth's. For example, on the Moon, the gravitational field strength is about 1/6th that of Earth's.

Key Takeaways:

• Mass is a measure of the amount of matter in an object and remains constant.
• Weight is a force that depends on both mass and the gravitational field strength.
• Gravitational field strength varies depending on location.
• Understanding the relationship between weight, mass, and gravitational field strength is essential for solving problems in physics.