NCERT Solutions Science for Class 8 Chapter 12 FRICTION | Class8 Science Chapter 12

NCERT Solutions Science for Class 8 Chapter 12 FRICTION available free in eteacherg.com। Here We learn class8 science Chapter 12 question answer concept of Microbe Friends and Enemies and and solve questions. NCERT Solutions Science for Class 8 Chapter 12 FRICTION. NCERT science Chapter 12 class 8 are part of NCERT class 8 science solution. Here we have given class8 science Chapter 12.

NCERT Solutions Science for Class 8 Chapter 12 FRICTION। Below these solutions consist of answers to all the important questions in NCERT book class 8th science Chapter 12. Here we solve Ncert class 8 science Chapter 12 question answer concepts all questions with easy method with expert solutions. It help students in their study, home work and preparing for exam. Soon we provide

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NCERT Solutions Science for Class 8 Chapter 12 FRICTION

class8 science Chapter 12

NCERT Solutions Science for Class 8 Chapter 12 FRICTION

science for class 8 Chapter 12 question answer

1. Fill in the blanks.

  (a) Friction opposes the _____________ between the surfaces in contact with each other.
  (b) Friction depends on the _____________ of surfaces.
  (c) Friction produces __________.
  (d) Sprinkling of powder on the carrom board ________ friction.
  (e) Sliding friction is ___________ than the static friction.

Answer : 

  (a) Friction opposes the motion between the surfaces in contact with each other.
  (b) Friction depends on the nature of surfaces.
  (c) Friction produces heat.
  (d) Sprinkling of powder on the carrom board reduced friction.
  (e) Sliding friction is less than the static friction.

2. Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Their arrangements are given below. Choose the correct arrangement.

  (a) rolling, static, sliding
  (b) rolling, sliding, static
  (c) static, sliding, rolling
  (d) sliding, static, rolling

Answer : (c) static, sliding, rolling

3. Alida runs her toy car on dry marble floor, wet marble floor, newspaper and towel spread on the floor. The force of friction acting on the car on different surfaces in increasing order will be

  (a) wet marble floor, dry marble floor, newspaper and towel.
  (b) newspaper, towel, dry marble floor, wet marble floor.
  (c) towel, newspaper, dry marble floor, wet marble floor.
  (d) wet marble floor, dry marble floor, towel, newspaper

Answer : (a) wet marble floor, dry marble floor, newspaper and towel.

4. Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.
Answer : When the desk is tilted the book slides down. The force of friction acts between the surface of the book and the desk and the direction of friction is opposite to the direction of sliding the book.

5. You spill a bucket of soapy water on a marble floor accidently. Would it make it easier or more difficult for you to walk on the floor? Why?
Answer : In this situation, it will be very difficult for us to walk on that floor because when soapy water spreads on the floor, the frictional force becomes very less and we have difficulty in walking.

6. Explain why sportsmen use shoes with spikes.
Answer : The player wears spiked shoes, as the wedge gives the correct grip in running. This is due to the force of friction. A wedge-shaped shoe will exert a force of friction.

7. 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?
Answer : When we try to push a heavy object, the force of friction increases. This is because when there is contact between two hard surfaces, more force has to be applied in order to reduce the blockage. Hence the boundary will have more frictional force.

8. Explain why sliding friction is less than static friction.
Answer : Static friction is the friction that exists between a stationary object and the surface on which it is at rest.
Spiral friction refers to the resistance created by any two objects when sliding along each other. This friction is also known as kinetic friction
Spiral friction is less than static friction due to the synapse of interlocking in two surfaces.

9. Give examples to show that friction is both a friend and a foe.
Answer : 
as friend –

  • We are able to walk only because of friction.
  • It is only because of friction that we can write on paper with the nib of a pen.

as an foe –

  • The sole of tires and shoes wear out quickly.
  • Heat is generated in the parts of the machine due to friction. It damages the machine.

10. Explain why objects moving in fluids must have special shapes.
Answer : The shape of objects moving in a liquid is made in such a way that their energy dissipation in overcoming friction while moving is minimal.

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