When two equal forces act in opposite directions, the net force becomes zero.

(i) Like poles repel each other.
(ii) Unlike poles attract each other.

Pressure = \(\frac { Force }{ Area } =\frac { 25 }{ 100 } \) = O.4Nm^-2 = 0.4 Pascals.

The force acting on a unit area of a surface is called pressure.

If two forces act in the opposite directions on an object, the net force acting on it is the difference between the two forces.

We are not crushed by the atmospheric pressure because air is present everywhere. The pressure of air inside our body is same as that of the atmosphere. Therefore, we do not experience its effect.

We make use of the relation between force, area and pressure to our advantage in many situations. To walk over a muddy patch of wet kachcha road without slipping, a wooden plank is used, the foundation is made wider than the width of the wall to be erected on it, width of tyres used for heavy vehicles like trucks and buses is larger than those used in cars or bicycles. On the other hand, tools meant for cutting and piercing always have a sharp edge. This ensures that the area of their surfaces in contact with the material to be cut pierced is as small as possible.

Yes, both the liquids and gases also exert pressure.

Due to broad feet of camels, they usually exert less pressure in the sand, so camels sinks less in the sand.

It is the force of gravity which is responsible for the grains to fall down. 

The interaction of poles of two magnets are
(i) Unlike poles attract each other
(ii) Like poles repel each other.

Yes, when we place our palm in front of a moving ball, then the palm apply a force on the moving ball and stop it.

Her friend should push the box towards East direction, so that it will start moving more fast towards East because the magnitude of force increases.