Lecture Notes on Weight and Gravitational Potential Energy

Understanding Gravity

Gravity: A force of attraction between two objects.
- Depends on:
  - The mass of the objects.
  - The distance between them.
Small objects (e.g., apples, buildings) have negligible gravitational forces.
Large distant objects (e.g., Jupiter) have weak gravitational effects due to distance.
Large nearby objects (e.g., Earth, Moon) exert stronger gravitational forces.
- Gravitational Field: The area of influence around an object.
- Gravitational Field Strength (g): The strength of this field.
  - Earth's gravitational field strength: 9.8 N/kg.
  - Moon's gravitational field strength: 1.6 N/kg.

Weight: The force experienced by an object in a gravitational field.
- Calculated as: Weight = Mass x Gravitational Field Strength
Example: A person with a mass of 60 kg on Earth's surface has a weight of 588 N (60 kg x 9.8 N/kg).
Distinction:
- Mass: An intrinsic property of an object.
- Weight: A force acting on an object due to gravity.
In physics, mass and weight are distinct but often confused in everyday language.

GPE: Energy required to lift an object against gravity.
- Formula: EP = mgh
  - m: Mass in kg.
  - g: Gravitational field strength in N/kg.
  - h: Height in meters.
- Measured in Joules (J).
Example Calculation:
- Object: Apple with mass = 100 g converted to 0.1 kg.
- Height: 3 meters.
- Calculation: EP = 0.1 kg x 9.8 N/kg x 3 m = 2.94 J.

Gravity is a force of attraction dependent on mass and distance.
Weight is calculated by multiplying mass by gravitational field strength (9.8 N/kg on Earth).
GPE is calculated using mass, gravitational field strength, and height.

For further learning, ensure to understand the differences between everyday language and technical physics terms regarding mass and weight.