Friction

Friction - NCERT Guide Science Class 8

Q1: Fill in the blanks:
  1. Friction opposes the ________ between the surfaces in contact with each other.
  2. Friction depends on the ________ of surfaces.
  3. Friction produces ________.
  4. Sprinkling of powder on the carom board _______ friction.
  5. Sliding friction is __________ than the static friction.
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Q2: Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Choose the correct arrangement:
  1. rolling, static, sliding
  2. rolling, sliding, static
  3. static, sliding, rolling
  4. sliding, static, rolling
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Q3: Alida runs her toy car on a dry marble floor, wet marble floor, newspaper and towel spread on the floor. What will be the force of friction in increasing order,acting on the car on different surfaces?
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Q4: Supposing your writing desk is tilted little. A book kept on it starts sliding down. Show the direction of frictional force acting on it. the car on different surfaces?
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Q5: You spill a bucket of soapy water on a marble floor accidentally. Would it make it easier or more difficult for you to walk on the floor? Why?
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Q6: Explain why sportsmen use shoes with spikes.
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Q7: Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
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Q8: Explain why sliding friction less than static friction.
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Q9: Give examples to show that friction is both a friend and foe.
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Q10: Explain why objects moving in fluids must have special shapes.
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