Page 79 - Genius Kidz Prudence Learning Sc-8

FORCE For Example, if a cupboard is pushed by three

Definition : Any influence that can cause individuals namely; A, B and C and the amount
motion or move some object is called as force. of force applied by each is F , F and F ,
3
2
1
respectively then the resultant force will be :
Interaction of Objects and Force :
F = F + F + F
Until and unless the body applying the force 1 2 3
does not interact with the body that needs to
F
be moved on, force will not act or motion will A 1
not occur.
F 2
B
For example :
F 3
C

But if another person D applies the force “F ”
4
on the same almirah in opposite direction.
Then the resultant force is :

F = F + F + F - F
1 2 3 4

F 1 F 4
A
Force produced by different objects
F 2
B
Exceptions : Exceptions include non-contact
F
force. An example of a non-contact force is a C 3
magnetic force.Magnetic force does not
require the two bodies to interact with each

other. Magnet can pull the iron nails even
If the force acting in opposite direction is equal
without touching.
to other applied force then resultant force is
equal to “0”.
For example, if F and F are the two forces
1 2
acting in opposite direction and F = F
1 2
Then resultant force = F – F = 0
1 2
Magnitude, direction and unit of force.
Magnitude of a force is its strength and it is
Magnet pulls iron nail measured in newton (N). Force required to lift
Resultant force : Total amount of force acting a body of 100 gm in vertical direction

on an object is equal to the resultant force. perpendicular to its surface is equal to 1 N.

It takes 8 mins 17 secs for light to travel from the sun's surface to the earth.

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