PHYSICS FORM 4 INERTIA
OBJECTIVES
• To know the exactly definition of inertia.
• To analyze the relationship between inertia and mass.
• To understand the effects of inertia in daily life experience.
MENU
• Definition of inertia• Relationship between mass inertia and m
ass.• Effect of inertia in our daily life• Quiz • Reference
Inertia is the property of matter that cause it to resist any change in its motion or state of rest
resistmenentang/ melawan
INERTIA makes the moving object continue to move at a constant speed in the same direction unless some external force changes the object’s motion
If the object is moving….
It tends to stay in that position unless some force puts that object into motion
If an object is at rest…
Inertia is not physical quantity and thus it does not have units
The property of inertia is found from the Newton’s first law of motion
Newton’s First Law of Motion
"An object at rest tends to stay at rest and an object in motion the same speed and in the same direction tends to stay in motion with unless acted upon by an unbalanced force"
•Constant wherever it is measured
•Base quantity•Scalar quantity•The SI unit of mass is
kilogram (kg)
If the motorcycle were to abruptly stop, then the rider in motion would continue in motion. The rider would likely be propelled from the motorcycle and be hurled into the
air. Once they leave the motorcycle, the rider becomes a projectile and continues in
projectile-like motion. It is because of inertia.
Applications of inertiaSome examples of using inertia in our daily life are :
1. The looses head of a hammer • To tighten the loose head of a hammer, knock one end of
the handle held vertically, on a hard surface. • The hammer head will continue on its downward motion• when the handle has been stopped, the top end of the
handle is slotted deeper into the hammer head.
2. The wet fur of cats and dogs.• Cats and dogs dry their wet fur by shaking their body
vigorously. • Water droplets on the fur tend to continue in motion when the
body has stopped shaking. • water droplets will be separated from the fur and fall away
3. To dislodge sticking chili sauce • Chili sauce in a bottle is poured out by a quick downward
movement of the bottle followed by a sudden stop. • The sauce in the bottle moves with the bottle during the
downward movement. • When bottle is stopped, the inertia of the sauce causes it to
continue on its downward movement and thus the sauce is forced out of the bottle.
4. Passengers in a bus • Passenger in a bus will lurch backward when a stationary bus
starts to move with forward acceleration. • The passenger were originally stationary. • When the bus started to move forward with an acceleration,
the inertia in the passenger made them maintain their original position.
When the cardboard covering the glass is pulled out quickly, the coin resting on the cardboard drops into
the glass
The inertia of the coins maintains it in its original
position (at horizontal/rest) even when one of the coin
is moved out quickly
When a student is riding a bicycle and runs over a
stone, he is thrown forward. Why does this happen?
ANSWER
THE INERTIA OF THE STUDENT MAINTAINS HIS
FORWARD MOTION SO THAT HE IS THROWN FORWARD WHEN HIS
BICYCLE IS MOMENTARILY STOPPED BY THE STONE