physics (ashutosh 9th d)

8/7/2019 Physics (Ashutosh 9th D)

1/14

Force & Laws of MotionForce & Laws of Motion

AshutoshAshutosh

99thth DD

RollRoll--No:No:--66


2/14

What is Force?

A push or pull acting on the body is

known as force


3/14

Two types of forceTwo types of force

Balanced Force

Unbalanced Force


4/14

Balanced ForceBalanced Force

When two forces of equal magnitude

When two forces of equal magnitudebut acting in opposite directions on anbut acting in opposite directions on an

object simultaneously,then the objectobject simultaneously,then the object

continues in its state of rest or ofcontinues in its state of rest or of

uniform motion in a straight line.suchuniform motion in a straight line.suchforces acting on the object are knownforces acting on the object are known

asas Balanced Force.Balanced Force.


5/14

Unbalanced ForceUnbalanced Force

When two forces of unequal magnitudesWhen two forces of unequal magnitudesact in opposite directions on an objectact in opposite directions on an object

simultaneously,then the object in thesimultaneously,then the object in the

direction of large force.T

hese forcesdirection of large force.T

hese forcesacting on the object are known asacting on the object are known as

Unbalanced Force.Unbalanced Force.


6/14

Laws of motion

There are three laws of motion:-

1.First law of motion2.Second law of motion

3.Third law of motion


7/14

First law of motion

According to this law everybody

continues in its state of rest or uniform

motion in a straight line unlesscompelled by some external force

(i.e.unbalanced force) to change that

state.


8/14

Second law of motion

According to this law,the change in

momentum of a body per unit time is

directly proportional to the unbalanced

force acting on the body and the

change in momentum takes place in the

direction of unbalanced force on the

body.


9/14

Third law of motionThird law of motion

Action and reaction are equal and

opposite.


10/14

Inertia

The tendency of a body to oppose or resist

any change in its state of rest or uniform

motion is called inertia of the body .

There are three types ofInertia:-

1.Inertia of Rest

2. Inertia of Motion

3. Inertia of Direction


11/14

Inertia of Rest

The tendency of a body to oppose any change in itsstate of rest is known as inertia of rest.

Example:-When a tree is viourously shakensome ofthe leaves fall from the trees.

When a tree is vigorously shaken,the branches ofthe tree come in Motion but the leaves tend to

continue in their state of rest due to inerria of rest.Asaresult of this leaves get separated from thebranches of the tree and hence fall down


12/14

Inertia of Motion

The tendency of a body to oppose any change in its

state of uniform motion is known as inertia of

Motion.

Example:-The passengers fall forward when a fast

moving bus stops suddenly.

This is because,the lower part of the bodies of thepassengers come to rest as soon as the bus

stops.But the upper part of their bodies continue to

move forward due to inertia of motion.


13/14

Inertia of Direction

The tendency of a body to oppose any change in its

direction of motion is known as inertia of direction.

Example:-When a fast moving bus negotiate a curveon the road, passengaers fall towards the centre of

the curved road.

This is due to the tendency of the passengers to

continue to move in a straight line.


14/14

Momentum

Momentum is nothing but product of

mass and velocity.

Momentum of fast running man is

more than that of running slow.

physics (ashutosh 9th d)

Documents