SCIENCE IN EVERYDAY LIFE PART- 2

The holding belts of a schoolbag are wide

Pressure is thrust per unit area. For a given thrust (force perpendicular to the surface), the

greater the area on which the force acts, the less is the pressure due to the force. The holding

belts of a school bag are made wide so that the pressure due to the weight of the schoolbag is

reduced by increasing the area. It is then easier to bear the load of the bag.

A sheet of metal that sinks in water can float if shaped like a pan.

A sheet of metal sinks in water because its density is more than that of water. If the sheet is

shaped like a pan, it can displace a large amount of water such that the up thrust on the pan

due to water balances the weight of the pan. Hence, it can float on water.

Ship entering fresh water from sea water sinks more.

The buoyant force due to liquid is proportional to the density of the liquid. Hence, the

volume of the liquid displaced by a floating body is inversely proportional to the density of

the liquid. The density of freshwater is less than that of seawater. Hence, a ship displaces a

greater volume of fresh water relative to that of seawater. Therefore, ship entering fresh

water from sea water sinks more.

A pointed nail can be easily hammered into wood than a blunt nail.

Pressure varies inversely as the area of the surface on which the force is applied, if the force

remains constant. The tip of a pointed nail has extremely small area while that of a blunt nail

has a comparatively large area. Therefore, a given force creates a large pressure on the

pointed nail and it can be easily hammered into the wood, while a very less pressures is

produced on the blunt nail by the same force and it cannot be easily hammered into the

wood.

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