![]() What are the two factors on which the force of friction depends? Rough surfaces have a larger number of irregularities and greater frictional force. When we move on any surface, we apply a force to overcome the interlocking of the surfaces. Nature of the surface is one of the factors affecting friction. How does the friction depend on the nature of the surface? The pointer moves on the scale showing the magnitude of the force. When a force is applied on it, the spring gets stretched. Rough surfaces: Surface of plyboard, unpainted wall, brick, tyres, etc.Ī spring balance is a device which measures the force acting on an object. Smooth surfaces: Surface of the mirror, surface of wet soaps, glazed tiles, surface of an oily pot, etc. Give some examples of smooth and rough surfaces. Rubbing of matchsticks on the rough surface to make fire.Rubbing of our hands to keep us warm in winter.Give some examples to show that friction produces heat. So it easily cuts through water and moves in it very easily. Why is it easier for the fish to swim in water?įish can easily swim in water because it has a streamlined body which produces less friction. The worn out tyres are discarded because their tread are worn off and limiting their effectiveness of providing required amount of friction. This force opposes the movement and the book stops. When we push the book on a table, a force is applied on it in the opposite direction of the motion called force of friction. If we push the book on the table, it stops after sometime. No Friction Class 8 Extra Questions Short Answer Questions When we try to move an object at rest, static friction comes into play. When does static friction come into play? Why?īy giving suitable shapes to bodies moving in fluids. Oil, creams and grease are called lubricants. Give some examples having streamlined body. The frictional force exerted by fluids is called drag.Ĭommonly gases and liquids are called fluids. Which force helps us to write on the paper or blackboard? ![]() Why does the jar of a mixer become hot when it is run for few minutes? Why is it difficult to walk on the wet marble floor? In order to reduce friction powder is sprinkled on carrom board. Why is fine powder sprinkled on the carrom board? Which surface does produce more friction-smooth or rough surface? Give one example where ball bearings are used.ĭoes friction depend on the nature of objects? What is the name of special shape given to objects moving in fluids? Why does a matchstick catch fire when rubbed on the rough surface of the box?ĭue to friction between the stick and rough surface a matchstick catches fire. To reduce friction and to pull them easily. Why do pieces of luggage fitted with rollers? Opposite to the direction of moving objects. What is the direction of force of friction acting on a moving object? Rolling friction is less than sliding friction. Why are wheels of vehicles made circular? What is the force responsible for wearing out of bicycles tyres? The irregularities on the two surfaces in contact is the cause of friction. The force acting on a moving object equal and opposite to the direction of motion is called force of friction.
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