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First Law: Everybody maintains its initial state of rest
or motion with uniform speed on a straight line unless
an external force acts on it. It is also called Galileo’s
law or law of inertia.
Example While jumping from a slowly moving
train/bus one must run for short distance, in the
direction of motion.
- Second Law: The form acting on an object is directly
proportioned to the product of the mass of the object
and the acceleration produced on it. - Third Law: To every action, there is an equal and
opposite reaction.
Example : Bogies of the trains are provided with
buffers to avoid severe jerks during shunting of trains.
Rocket moves up due to reaction of downward
ejection of gas.
CIRCULAR MOTION - When an object moves along a circular path, its
motion is called circular motion. - The external force required to act radially inward over
the circular motion of the body is called Centripetal
force. - Centrifugal force is such a pseudo force that. is
equal and opposite to Centripetal force. - Cream separator, centrifugal dryer work on the
principle of centrifugal force.
FRICTION
- In the opposing force that is set-up between the
surfaces of contact, when one body slides or rolls or
tends to do so on the surface of another body. - Due to friction, we are able to move on the surface of
Earth. - While applying brakes in automobiles, it stops only
due to friction.
Pascal’s Law of Pressure - Hydraulic lift, hydraulic press and hydraulic brakes are
based on the Pascal’s law of pressure.
Archimedes Principle - When a body is immersed partly or wholly in a liquid,
there is an apparent loss in the weight of the body,
which is equal to the weight of liquid displaced by the
body. - The weight of water displaced by an iron ball is less
than its own weight. Whereas water displaced by the
immersed portion of a ship is equal to its weight. So,
small ball of iron ball sink in water, but large ship float. - A fat person will quickly learn the swimming as
compared to a slim person because he will displace
more water. So, it will be more balanced. - Hydrogen filled balloon float in air because hydrogen
is lighter than air. A person can lift more weight in
water.