Friction - Chapter Wise CBSE Solved Question and Answer Based On NCERT
Very Short Q&A:
Q1: Define friction
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Friction is the "evil" of all motion. No matter which direction something moves in, friction pulls it the other way.
Q2: Why vehicles slow down when brakes are applied?
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Because of friction.
Q3: Friction opposes the ________ between the surfaces in contact with each other.
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Relative motion.
Q4: Friction produces
Light
alpha rays
Heat
All of the above
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Heat.
Q5: The force of friction always opposes the _________ force.
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Applied
Q6: Is friction is same for all the surfaces?
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No
Q7: Force of friction is greater in case of rough surface or smooth surface?
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Rough surface.
Q8: Define static friction.
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Static friction is the friction between two or more solid objects that are not moving relative to each other. For example, static friction can prevent an object from sliding down a sloped surface.
Q9: Define sliding friction.
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Sliding friction is friction caused by moving two flat surfaces against each other.
Q10: Give examples to support the statement that- “friction is important for most of our day to day activities”.
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For writing with pen or pencil, for fixing nail in the wall, for lightening of a matchstick etc. friction is used.
Q11: Give an example to show friction produces heat.
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Rubbing of our palm makes we feel warm.
Q12: Why trucks tyres are treaded?
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Trucks tyres are treaded to increase friction so as to provide better grip with the ground.
Q13: Why sole of shoes are grooved?
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Sole of shoes are grooved to increase friction so as to provide shoes, a better grip on the floor.
Q14: _____________ is used to increase friction in the brake system of automobiles.
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Brake pads.
Q15: Why kabbadi players should rub their hand with soil before they start playing?
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For a better grip of their opponent.
Q16: Powder is sprinkled on the carom board to reduce ____________________.
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Friction
Q17: Define lubricants.
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A lubricant is a substance used to reduce friction between moving surfaces. It may also have the function of transporting foreign particles.
Q18: Can we reduce friction to zero by using lubricants?
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No it is not possible to entirely eliminate friction.
Q19: What is spring balance?
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Spring balance is the weighing device which is used for measuring the force acting on an object.
Q20: Rolling increases friction. True / False
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False.
Q21: Why sliding is replaced by rolling in most of the machines?
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Because rolling friction is smaller than sliding friction.
Q22: Give some examples showing replacement of sliding with rolling in machines.
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The use of ball bearings between hubs and the axles of ceiling fans and bicycles.
Q23: Common name of gases and liquid is ________________.
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Fluids
Q24: Define drag.
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The frictional forces exerted by fluids are called drag.
Q25: Water and other liquid exerts _________________ when objects move through them.
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Force of friction
Q26: Sliding friction is ______________________ than the static friction.
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Smaller
Q27: Arrange forces due to rolling, static and sliding frictions in a decreasing order.
rolling, sliding , static
sliding, static, rolling
static, sliding, rolling
None of these
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static, sliding, rolling.
Q28: Name the force responsible to fall down a boy when he steps on a banana peel.
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Force of friction
Q29: Friction depends upon __________________ of the surface.
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Nature
Q30: Name the device used for measuring force acting on an object.
