FORCE AND LAWS OF MOTION

FIRST LAW OF MOTION

An object in motion

• Galileo studied on the motion of object that

An object in motion...• If the right-side plane were ultimately made

horizontal (that is, the slope is reduced to zero), the marble would continue to travel forever trying to reach the same height that it was released from.

An object in rest A stationary object will remain in rest until

an external force is acted on it.

These objects will not move unless an external force act on it.

Inertia• If an object is at rest it tends to

remain at rest; if it is moving it tends to keep moving. This property of an object is called its inertia. • The resistance an object has to a

change in its state of motion.

SIR ISSAC NEWTON

•Galileo’s theory was further studied by Newton. And he

formulated three laws of motion.

First law of motion The first law of motion is stated as:

An object remains in a state of rest or of uniform motion in a straight line unless compelled to change that state by an applied force. This is also called as LAW OF INERTIA

Some examples When force is applied to the card, why the

coin falls inside the glass?

And now the answer This is due to the INERTIA of the coin. At first both the coin and the card are in rest. Then an external force is applied only to the

card not to the coin. So the coin which in rest is remains in rest

due to inertia. Thatswhy the coin falls inside the glass.

Some examplesAn astronaut

in outer space away

from gravitationa

l or frictional

forces throws a rock. The

rock will…..

And now the answer The rock will continue to move in a straight line at a constant speed.

The rock’s tendency to do this is called INERTIA.

Application to everyday life

Opening a bottle Removing dusts from cloths Seat belts Seismometer