Force & law

ASSIGNMENT REPORT NO-1TOPIC: FORCE & LAWS OF MOTIONGUIDED BY : SIR UDAY PAL(PGT)

Class:IX Sec:B Roll No:28

FORCE:

Force is an external agency which can change the state of rest or motion of configuration of a body.

Force are of two types: Balanced force

Unbalanced force

Balanced force:

When a number of forces acting simultaneous on a body do not

bring about any change in its state of rest or of uniform motion in a straight line ,then it is balanced

force.

Unbalanced force:

When a number of forces acting simultaneously on a body bring

about a change in state of rest or uniform motion in a straight line ,then it is known as unbalanced

force.

Balanced force:

Unbalanced force:

Effects of force:

Force can bring a stationary body in motion.

Can stop a moving body.

Can change the direction of a moving body.

Can change the speed of a moving body.

Effects of force:

Galileo’s Experiment:

According to Galileo,a uniform motion in a straight line did not require any force to maintain it.

So if a body is in motion,it will continue to move with the same speed & along the same straight line if it is left to itself & no external influence acts on it.

Galileo’s law of Inertia:

When no unbalanced force is exerted on a body ,it stays at rest or moves in a straight line with constant speed ,i.e. it will remain unaccelerated.

Inertia:

The inherent property of a body by virtue of which it resists any change in its state of rest or of uniform motion in a straight line on its own , is called inertia.

Mass is the measure of inertia.

First law of motion:

Second law of motion:

Third law of motion:

Conservation of momentum:

Sum of momenta of two objects before collision is equal to sum of momenta after the collision provided there is no provided unbalanced force acting on them.

This is known as Law of Conservation of Momentum.