Question

Give Reasons:
1. Oil is applied to the moving part of a machine.
2 Sparks are produced when a pair of scissors is sharpened against a grinding wheel.
3.A piece of chalk wears out as it is used on a black board.​

Answer 1

Answer:

1) as oil reduces the wear and tear of the machine it is applied on machine parts.

2) Sparks are produced because of the generation of heat energy between the pair of scissors and blade due to friction

3) a piece of chalk wears out because at each use the particles of chalk stick to the black board.

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Answer 2

Answer:

1 .The oil is applied to the moving parts of machine to lessen friction and avoid rusting.

2. The sparks are produced because of the friction generated from rubbing of metal to metallic surface.

3. The chemical formula of chalk is CACO3 and when we are writing on a black board due to friction and atmospheric pressure it wears out

Hope it helps