Almost all the things in our daily life are possible because some sort of force. Presence and even absence of force play important role in different situations. This presentation is about 'Forces'. It describes all the types of forces with appropriate and familiar examples.

1. Forces
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2. Observe the following
pictures. Some kind of
force is needed for an
object to move or to
change shape or to
change its position.
Force is also needed
to change the speed
or direction of a
moving object.

3. Types of forces
1. Muscular force:
The force applied using parts of the body like
arms or legs is called muscular force.
Eg. While playing cricket or football, players
apply muscular force on the ball. Force applied
through the use of animals like
bullocks, horses, elephants is also muscular
force.
2. Mechanical force:
Force applied by using
machines is called mechanical
force.
eg. This type of force is used
in most of the commonly used
machines like pump or vehicles
like tractors etc.

4. 3. Gravitational force:
Force applied by the earth is called
gravitational force. Gravity acts on every
object.
Any object thrown upwards reaches a
certain height and then falls down. It
happens because of gravity. As a result of
gravity, the motion of an object thrown
upwards gradually decreases and
eventually becomes zero; after that it
begins to fall downwards.
When we lift something we have to apply
force against gravity. The greater the
mass of an object, the greater is the
force of gravity acting on it.

5. 4. Magnetic force:
The force exerted by a magnet is called
magnetic force.
Eg. In some goods yards, there are
cranes with magnets. These are used to
lift heavy loads.
The maglev train – Magnetic levitation
(maglev) - Scientists have designed a
train which gets lifted up above the
tracks and travels with very high speed
in air. (500-580 km per hour). It is
based on the principle of magnetic
repulsion between like poles of a
magnet.

6. 5. Frictional force:
A certain force acts between a moving object
and the surface along which it moves. This
force is called friction.
Friction always acts in a direction opposite to
the motion of the body.
Friction between different surfaces is
different.
eg. Can you walk on a greasy floor? No.
Because there is no friction, you can not walk
on it. But the same grease helps your vehicle
work smoothly.
Have you observed ramps of the shopping
mall or airport are purposely made rough so
that people won’t slip while walking? On the
other hand, surface of the ‘slide’ in the park
is made very smooth so that you can slip
quickly on it.
Presence and even absence of friction play
important role in different situations.

7. 5. Static electric force:
Spread small pieces of paper on a
table. Rub a plastic comb on dry
hair. Bring both the things close
to each other. What do you see?
Pieces of paper move close to the
comb. Rubbing causes electricity
to develop on substances like
rubber, plastic and ebonite. This
force that is electricity
produced due to friction is called
static electric force. This force
is weaker than other types of
force. It is obtained by rubbing a
particular substance on one
another.

8. Activity
No. Action Force applied
1 Sprinkling talcum powder
on a carom board.
2 A potter turning his wheel
3 Ball bearings in machines
4 Applying brakes on a
bicycle
Visit a nearby garage. Observe different
activities happening there like oiling a
vehicle, repairing etc. Observe and study
different forces used in different parts of a
vehicle.