Page 62 - Innovator's Science-8

because gravity on the Moon is one-sixth that of the Earth.

This shows that weight changes from place to place, but mass remains
the same everywhere.

Magnetic Force

Magnetic force refers to the force exerted by a magnet on a magnetic
substance. This force acts on an object from a distance. However, when

the force has acted upon the object, they comein physical contact with
each other. Magnetic force finds its application in a number of areas like
Magnetic force separating scrap iron from a heap of garbage.

Activity-1 Aim: To show the effect of gravita onal force on the object of different weights
Materials Required: A spring balance, a small polythene bag, one big and one small
Experiential Learning
pieces of stone, pen and notebook
Procedure: Take the spring balance and set its pointer
at zero (0) mark. Now, hang the polythene bag in the
hook of the spring balance and place smaller piece of
the stone in it. Note down the reading shown by the
spring balance. Then, remove smaller piece from the
polythene bag and place bigger piece of stone in it.
Again, note down the reading of the spring balance.
What do you observe?
Observa on: The spring balance shows greater reading in case of a bigger piece of
stone.

Conclusion: The earth pulls the bigger piece of stone with larger gravita onal force
as compared to the smaller piece. When we weigh an object using a spring balance,
we actually measure the earth’s gravita onal force ac ng on the object.

(Note: If we weigh the same object on the surface of the moon using a spring
balance, we will find that its weight is less than what it weighs on the earth. It is
because the moon has a smaller force of gravity as compared to that of the earth.
The gravity on the moon is 1/6 of the earths’ gravity.)

Electrostatic Force

After combing your hair, when your bring the comb close to bits of
paper, they are attracted towards it. This force is an example of action at

a distance force and is called electrostatic force . We can understand it
with the help of another example.

Activity-2 Put some iron nails on a sheet of paper. Bring a small magnet near these iron nails.
You will see that iron nails are pulled towards the magnet even when they are a li le
Experiential Learning
distance away from it. This shows that magne c force can act from a distance.

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Science-8