2. INERTIA
• Inertia is a word we use when we talk about matter and movement.
• Inertia is the quality in matter (matter is anything you can touch) that
lets it stay still if it is still, or keeps it moving if it is moving.
• If you want to overcome inertia, you have to apply a force.
• A force will make something that is still start to move, like flicking a
wad of paper with a pencil will make it move.
• Also force, due to resistance, will slow or stop something that is already
moving.
• The wad of paper will be slowed by resistance made by rubbing up
against the air it is passing through.
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3. TYPES OF INERTIA
•Inertia of rest
•Inertia of direction
•Inertia of motion
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4. Inertia of rest
• Inertiaof rest is defined as the propertyby virtue
of which a bodycontinuesto be at rest unless
acted by some external forceto changethat
condition.
• inertia of motion is definedas the propertyby
virtueof which a body continues to be in motion
along a straightlineunless acted upon by some
externalforceto changethat condition.
• inertia of motion alonga particular directionis
definedas the propertyby virtueof which the
bodycontinuesin that particulardirectionunless
acted upon by some forceto changethat
direction.
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5. Inertia of direction
• A body moving in a certain direction cannot change
its direction without any force being applied on it.
• It is the property due to which a body maintains its
sense of direction.
• Ex: When we travel by a motorcar and if it makes a
sharp turn at a high speed, we tend to get thrown to
one side.
• This is an explanation for the law of inertia.
• We have the tendency to continue in our straight-
line motion.
• When an unbalanced force is applied to change the
direction of motion of the motorcar, we slip to one
side of the seat due to the inertia of direction of our
body.
6. Inertia of motion
• If a bodyis in a stateof motion, then it will continueto move at
the same speed in the same directionunlessan externalforceis
applied to changeitsstate.
• examples of inertia of motion in dailylife:
• when seated on a motorcycleand the motorcyclistsuddenly
applies brakes, we get a push in the forward direction.
• thisis becausewe were in motion,and inertia tendsto oppose
the changein our state.
• when a personjumps out of a movingbus, he tends to move
ahead or fall down.
• thisis becausehe was in motion.
• on jumping, his feet touch the groundbut the rest of the body
still tendsto remainin motion.
