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RELATING TO THE PREVIOUS CHAPTER We learnt that:
Force = mass x acceleration Weight is a force, therefore,
Weight = mass x gravitational acceleration
W = mg
ON THE MOON...
Did Buzz Aldrin lose any mass? What does Neil Armstrong mean?
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
COMMON MEASUREMENT INSTRUMENTS
Electronic balance
Newton-meter (Spring balance)
Mass Weight
SUMMARYMass 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
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
INERTIA Force is needed to overcome inertia.
Inertia depends on mass and not weight
The greater the mass, the greater the inertia.
IN A MOVING VEHICLE Sudden braking Round a corner
GRAVITATIONAL FIELD
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.
GRAVITATIONAL FIELD Near the Earth’s surface, the
gravitational field is uniform The field lines are drawn parallel to
each other
UNITS ANALYSIS Using W = mg,
g = W/mUnits of g is N/kg
Recall free-fallUsing F = maAcceleration due to gravity is 9.8 m/s^2Units of g is also m/s^2