1. Weight is defined as the gravitational force acting on an object. The weight (W) of an object with mass (m) can be calculated as W = mg, where g is the acceleration due to gravity. 2. While an object's mass stays constant, its weight can change depending on the gravitational field. For example, an object weighs 1/6 as much on the moon as on Earth due to the moon's lower gravitational acceleration. 3. Examples calculate the gravitational field strength and weight of objects on different planets or celestial bodies using the equation W = mg.

1. Objective:
Students must be able to state
weight as the gravitational force
that acts on an object.
W = mg
2.8 WEIGHT

2. WhatisMASS??
WhatisWEIGHT??

4. F = ma
W = mg
PREVIOUS……
 Gravitational force acting is
weight, W.
 Acceleration is gravitational
acceleration, g.

5. MassandWeight
Mass, m Weight, W
The quantity of matter
in a body
The gravitational force
acting on the object.
Scalar quantity Vector quantity
Unit : kg Unit : Newton
The value is constant
everywhere
The value change depend
to the gravitational field

6. WEIGHT
Weight is defined as the gravitational force acting
on the object.
For an object of mass m , the weight is calculated as
Weight , W = mg
Where g = acceleration due to gravity
This lunar exploration vehicle that this
astronaut is driving on the moon has the
same mass that it has on the earth.
However, its weight on the moon is only
1/6 its weight on the earth.

7. ACCELERATION DUE TO
GRAVITY

8. WEIGHT
Mass 100 kg 100 kg 100 kg
Weight No weight 160 N 1000 N
The mass is always constant but the weight
depends on where it is measured.

9. EXAMPLES
3. A 10 kg object has a weight of 150 N on a planet.
(a) What is the gravitational field strength on the planet?
4. An astronaut of mass 60 kg is assigned to explore the Moon. What is the
astronaut’s weight on the Moon’s surface?
m = 10 kg
W = 150 N
g = ?
W = mg
𝑔 =
𝑊
𝑚
=
150
10
= 1.5 𝑚𝑠−2
m = 60 kg
W = ? N
g = 1.62 𝑚𝑠−2
W = mg
𝑤 = 60 1.62
= 97.2 N