2. Inertia is the property of matter
that cause it to resist any
change in its motion or state of
rest
3. If the object is
moving….
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.
This is known as inertia of motion.
4. If an object is at
rest…
It tends to stay in that position
unless some force puts that object
into motion.
This is inertia of rest.
5. 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
6. 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"
8. RELATIONSHIP
BETWEEN MASS AND
INERTIA
An object with larger mass have
larger inertia
When mass increases inertia
also increases
9.
10. Applications of inertia
Some 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.
11. 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
12. 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.
13. 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.
14. ANSWER
When the cardboard covering the
glass is pulled out quickly, what will
happens to the coin?
15. When the cardboard covering the
glass is pulled out quickly, the coin
resting on the cardboard drops into
the glass
16. What will happen to the
rest of the coins when one
of the coin is moved out
quickly?
17. The inertia of the coins
maintains it in its original
position (at horizontal/rest)
even when one of the coin
is moved out quickly
