The document discusses the difference between mass and weight. It states that mass remains constant regardless of location, while weight varies depending on the gravitational acceleration. Mass is measured in kilograms using a balance, while weight is measured in Newtons using a spring scale. The gravitational acceleration on the moon is about one-sixth that of Earth.

1. RELATING TO THE PREVIOUS
CHAPTER
 We learnt that:
Force = mass x acceleration
 Weight is a force, therefore,
Weight = mass x gravitational
acceleration

2. ON THE MOON...
 Did Buzz Aldrin lose any mass?
 What does Neil Armstrong mean?

3. MASS VS. WEIGHT
 Mass of an
object will be
the same no
matter where
the object is
located
 Weight of an
object will vary
according to the
gravitational
force
experienced by
the object
Acceleration due to gravity on the
moon is one-sixth that of Earth

4. COMMON MEASUREMENT
INSTRUMENTS
 Electronic balance  Newton-meter
(Spring balance)
Mass Weight

5. SUMMARY
Mass Weight
The amount of
substance in the body
The force of gravity
acting on the body
Constant in any location Depends on the
acceleration due to
gravity at the location
Scalar quantity Vector quantity
Measured in kilograms Measured in Newtons
Measured using a beam
balance or electronic
balance
Measured using a spring
balance

6. INERTIA
 All bodies with mass possess a property
called inertia
 The inertia of an object is the
reluctance of the object to change its
state of rest, or if it is moving
 Consistent with Newton’s first law

7. INERTIA
 Force is needed to overcome inertia.
Inertia depends on mass and not weight
 The greater the mass, the greater the
inertia.

8. IN A MOVING VEHICLE
 Sudden braking
 Round a corner

10. GRAVITATIONAL
FIELD

11. GRAVITATIONAL FIELD
 A gravitational field is a region where a
mass experiences a force due to
gravitational attraction.
 Gravitational field strength, g, is defined
as force per unit mass.

12. GRAVITATIONAL FIELD
 Near the Earth’s surface, the
gravitational field is uniform
 The field lines are drawn parallel to each
other

13. UNITS ANALYSIS
 Using W = mg,
 g = W/m
 Units of g is N/kg
 Recall free-fall
 Using F = ma
 Acceleration due to gravity is 9.8 m/s^2
 Units of g is also m/s^2