Friction - Chapter Wise CBSE Solved Question and Answer Based On NCERT
Long Q&A:
Q1: Explain why friction is a necessary evil?
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Ans:
Friction is very important for us it helps in:,It allows us to walk comfortably, It allows us to grip and catch other objects. Things do not move from their places because of the friction. Speeds of moving objects can be controlled due to friction only. But apart from this friction is considered as an evil because; it causes wear and tear in objects of our daily use including machines. It makes movement of heavy objects very difficult.We need to spend a lot of time and money for the maintenance of various machines in order to keep their friction low.
Q2: Force of friction increases when two surfaces are pressed harder? Justify the statement.
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Ans:
Friction is caused by interlocking of irregularities in the two surfaces, thus it is quite obvious that the Force of friction increases when two surfaces are pressed harder, this can be experienced by dragging a mat when no one is sitting on it, and when a person is sitting on it.
Q3: Explain increasing and reducing friction.
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Ans:
Soles of shoes are grooved so that a better grip is provided to the surface and thus can move safely and freely on floors. The tyres of vehicles are treaded to provide better grip with the ground. Powder is sprinkled on the carom board to reduce friction and increase efficiency. Friction can never be entirely eliminated, because no surface is perfectly smooth, there are always some irregularities present in it.
