Page 60 - Innovator's Science-8

FORCE

Force is defined as the push or pull on an object. When things are moved
changing their position, force plays a very important role. Some common
applications of force in our everyday life are–

• Force applied to open or close the door.
Push
• Lifting of your school bag or any kind of luggage.
• Kicking a football.
• Animal pulling a cart.

• All objects being attracted towards the Earth.

So, force is that pull or push which can change the state of motion or rest
of an object. It can change the shape, size or dimensions of an object.

Pull
TYPES OF FORCE
A force is a push or pull on an objet resulting from the object's
interaction with another object. The SI unit of force is Newton and its

symbol is . The interaction between the objects may be :
N
• Contact force
• Non-contact force or action at a distance force

1. Contact Force

When force acts between two objects and when they are in physical
contact with each other, the force is said to be contact force . For
example, when a footballer kicks the ball with his leg, the ball and the leg

are in contact with each other, thus it is a contact force. Contact force
may further be classified into–
• Muscular force

• Frictional force
• Mechanical force

Muscular force

The force applied by our muscles in doing any activity is termed as
muscular force. Pushing the door, lifting up a heavy box, opening the
table drawer, all require muscular force. Muscular force is also referred
to as the biological force. At times, it so happens that human muscular

force is not sufficient to complete a task. In that case, we take help of
Muscular force
other living things like horses, bullocks, etc.
There are instances when animal force is also insufficient, then we take

help from non-living things like pulley or other simple machines.

60
Science-8