(i) Aryan applied more pressure on his palms by bearing the maximum load of his body on small area of palms while Mridul applied pressure on his palms by bearing the same load on larger area of palms.
(ii) Mridul had the presence of mind and he thought of an excellent idea about pressure on the body part.

The force which always acts on all the moving objects and whose direction is always opposite to the direction of motion is called force of friction. Since the force of friction arises due to contact between surfaces, it is also called contact force.

The buses and trucks are heavy and require to exert less pressure. We know that pressure decreases as area of contact increases, so the tyres are broadened so that they exert less pressure on earth and move easily. If they exert more pressure, they will sink in earth. The scooters and cars have less wide wheels because they need more pressure for gripping.

A force changes or try to change the :
(i) speed of a moving body.
(ii) direction of motion of a body.
(iii)shape of a body.

The envelope of air surrounding the earth is known as the atmosphere. The pressure exerted by this air is known as atmospheric pressure. The magnitude of atmospheric pressure can be felt by following experiment. Take a good quality rubber sucker. Press it hard on a smooth plane surface. When we press the sucker, most of the air between its cup and surface escapes out. The sucker sticks to the surface because the pressure of atmosphere acts on it. To pull the sucker off the surface, the applied force should be large. This activity might give us an idea about the magnitude of atmospheric pressure.

Effect of the force in given situations:
(i) While taking a penalty kick in football the player applies a force on the ball. Before being hit, the ball was at rest and so its speed was zero. It indicates that an object can move from rest with effect of force.
(ii) A car is moving on the road at a slow speed. Applying force on the accelerator will increase the speed of the car.
(iii)Take lump of dough in a plate. Make chapatis from that dough by rolling roller and putting pressure on it. It changes the shape by force.

Take a glass tube open at both ends. The length of tube should be about 15 ern. Take a thin sheet of a good rubber. Stretch the rubber and fix tightly over one end of the pipe. Hold the tube in vertical position. Pour water in it. The rubber sheet bulges out. This bulging is due to the pressure exerted by water. Hence it is proved that pressure is exerted by liquids.

Because the area of pointed end of the nail is much smaller than that of its head. The same force, therefore produces a pressure sufficient to push the pointed end of the nail into the wooden plank.

Blunt knife has larger area than of sharp knife. So less pressure will be on vegetable which makes it tough to cut.

The force responsible for wearing out tyres of motor vehicle is force of friction.

Non-contact forces:
(i) Gravitational force
(ii) Magnetic force
(iii) Electrostatic force.

The force responsible for changing the state of motion of ball is the force of friction. The ball will come to rest position. This force causes wear and tear of the objects in motion.

Contact forces can be of two types:
(i)Muscular force
(ii) Force of friction.

The state of motion of an object is described by its speed and the direction of motion. An object may be at rest or in motion, both are its states of motion. It can be changed by action of force on that object.

The force on unit area is called pressure, works on the chapatis. This is the pressure which works on the dough balls and make them chapatis with the help of machine.