# Understanding Gravity

Card 1: Gravitational Field

## Gravitational Field

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

Card 2: Gravitational Field Strength

## 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

Card 3: Formula of Gravitational Field Strength

## Gravitational Field Strength Formula

Card 4: Gravitational Acceleration

## 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.
Card 5: Comparing gravitational field strength and gravitational acceleration

## 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.
Card 6: What is weight?

## Weight

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

Unit: Newton (N)

Card 7: Differences between Weight and Mass

## Differences between Weight and Mass

 Weight Mass Depends on the gravitational field strength Independent from the gravitational field strength Vector quantity Scalar Quantity Unit Newton (N) Unit: Kilogram (kg)
Card 8: What is free falling?

## 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.

Card 9: Free falling case 1 - Falling from high place

## Falling from high place

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

Card 10: Free falling case 2 - Launching object upward

## Launching object upward

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

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