Weight is the force exerted on an object due to gravity. It is a measure of the gravitational attraction between two objects, specifically the mass of the object and the gravitational field strength.
Concept of Weight
Weight is a vector quantity, meaning it has both magnitude and direction. The direction of the weight force is always towards the center of the Earth.
The magnitude of the weight force can be calculated using the following formula:
$$W = mg$$
Where:
W is the weight of the object (measured in Newtons, N)
m is the mass of the object (measured in kilograms, kg)
g is the acceleration due to gravity (approximately 9.8 m/s2 near the Earth's surface)
Factors Affecting Weight
The weight of an object depends on two factors:
Mass: The more massive an object, the greater the gravitational force acting on it, and therefore the greater its weight.
Acceleration due to gravity (g): The value of 'g' varies slightly depending on the object's distance from the Earth's center. It is approximately constant near the Earth's surface.
Weight vs. Mass
It is important to distinguish between mass and weight:
Mass: A measure of the amount of matter in an object. Mass is a scalar quantity and remains constant regardless of location.
Weight: The force exerted on an object due to gravity. Weight is a vector quantity and can change depending on the gravitational field strength.
Property
Mass
Weight
Definition
Amount of matter in an object
Force due to gravity on an object
Type of Quantity
Scalar
Vector
Variation with Location
Constant
Varies with gravitational field strength
For example, an astronaut will have the same mass on Earth and on the Moon, but their weight will be different because the Moon has a lower gravitational field strength than the Earth.
Suggested diagram: An object on Earth and the Moon, illustrating the difference in weight due to varying gravitational field strengths.