REVISION QUESTION FOR CLASS 8

FRICTION

• Fill in the blanks:	(1 marks each)

(    (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.

(6)Polishing a rough surface _____________ Friction.

(7)Friction _____________ motion.

(8)Friction is caused by the _____________ of the surfaces in contact.

(9)The force of friction _____________ Depend on the area of the surfaces in contact.

(10)The force of friction between two surface always _____________ motion.

VERY SHORT ANSWER QUESTION.

1.What is force of friction?

2.Does friction depend on the nature of the objects ? 

3.Which surface produces more friction?

4.How many types of friction are?

 5.What is the direction of frictional force? 

6.What does friction produce?

7.Write one harm of friction?

 8.When Does rolling come in play?

9.Can we eliminate friction completely?

 10.What are fluids?

• SHORT ANSWER QUESTION.

(2 - 3 marks )

1.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.

2.You spill a bucket of soapy water on a marble floor accidental. Would it make it easier or more difficult? For you to walk on the floor? Why?

3.Explain why sportsmen use shoes with spikes.

4.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?

5. Give examples to show that friction is both a friend and a foe.

6.On what does the frictional force on an object in a fluid depend?

7.Is force of friction a contact on non-contact force?

8.Why are the types of automobiles made corrugated and rough?

ANSWER THESE QUESTIONS

1. What are static and sliding friction?

2.Why is it not easy to move an object from its static position? 3.Mention three examples which show that friction produces heat?

4.Why do we need to Decrease friction and how it can be decreased?

5.Why do We shape aeroplane like that of a bird?

• LONG ANSWER QUESTIONS:

5 Marks Each

1.What is sliding friction? Explain why the sliding friction is less than the static friction.

2.What are lubricants? Explain why objects moving in fluids must have special shapes.

3.Explain friction as a friend and foe with examples.

4.Explain advantage and dis advantage of friction?

5.Explain various types o friction?

• MULTIPLE CHOICE QUESTION:	1-Marks Each
1. 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

2.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 :

(i)Wet marble floor, dry marble floor, newspaper and towel. 

(ii) Newspaper, towel, dry marble floor, wet marble floor