20. (1) Give reasons:
a) Kabaddi players rub their hands with sand
b) We sprinkle powder on carom board
(ii) 'Friction is a necessary evil'. Justify this statement
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Answers
Answer:
to make their hand rough
answer of a
same answer
of b
other I don't know
sorry dear
Answer:
Liquids exert pressure on the walls of the container. This can be demonstrated by fitting a rubber sheet on the glass tube and filling the glass tube with water.On increasing the level of water in the bottle, there is a greater bulge in the balloon. Pressure increases because of increase in water column.this proves liquids exert pressure on the base or bottom and walls of their container.
a)Kabaddi players rub their hands with soil so that they get a better grip on their opponents. It involves grabbing their opponents so sand decreases the tendency of slipping due to sweat.
b)we sprinkle powder on carrom board to reduce the friction between the surface of the carrom board,between the striker and the coin..as a result the coin moves smoothly ans easily much force isn't required..
ii)Frictional force causes a lot of losses in general almost all crucial tasks cannot be carried out without the presence of friction.Basic activities like walking and writing are possible due to friction. Hence it is considered as a necessary evil ...
