Understanding Gravity

Gravitational Field

A gravitational field as a region in which an object experiences a force due to gravitational attraction

Gravitational Field Strength

The gravitational field strength at a point in the gravitational field is the gravitational force acting on a mass of 1 kg placed at that point.

Unit: N/kg

Symbol: g

Gravitational Field Strength Formula

Gravitational Acceleration

The gravitational acceleration is the acceleration of an object due to the pull of the gravitational force.

Unit: ms-2

Symbol: g

Important notes:

• Gravitational acceleration does not depend on the mass of the moving object.
• The magnitude of gravitational acceleration is taken to be 10ms-2.

Gravitational Field Strength vs. Gravitational Acceleration

• Both the gravitational field strength and gravitational acceleration have the symbol, g and the same value (10ms-2) on the surface of the earth.
• When considering a body falling freely, the g is the gravitational acceleration.
• When considering objects at rest, g is the Earth’s gravitational field strength acting on it.

Weight

The weight of an object is defined as the gravitational force acting on the object.

Unit: Newton (N)

Differences between Weight and Mass

Free Falling

Free falling is a motion under force of gravity as the only force acting on the moving object.

Practically, free falling can only take place in vacuum.

Falling from high place

Acceleration = 10ms-2
Initial velocity = 0
Displacement = high of the location

Launching object upward

Acceleration = -10ms-2
Velocity at maximum height = 0