class 8 revision worksheet on friction
1.   Complete the sentence. Friction always ____________

       a. helps the motion

       b. opposes the motion

       c. both of these

       d. none of these

2.   Which one of these characteristics does a smooth surface has?

       a. Less frictional force

       b. More frictional force

       c. Sometimes less and sometimes more force

       d. All of above

3.   Friction is a __________

       a. Contact force

       b. Non-contact force

       c. Magnetic force

       d. None of these

4.   What kind of substances are known as lubricants

       a. Increase friction

       b. Decrease friction

       c. Increase or decrease friction

       d. None of these

5.   Fluid are____

       a. Gases

       b. Liquids

       c. Gases and liquids both

       d. None of these

6.   On what force of friction depends?

       a. Smoothness of surface

       b. Roughness of surface

       c. Inclination of surface

       d. Al of above

7.   Friction is a /an_______

       a. Evil

       b. Foe

       c. Both (a) and (b)

       d. None

8.   Lubricants ________

       a. Increase friction

       b. Reduce friction

       c. Both (a) and (b)

       d. None

9.   Rolling friction is smaller than?

       a. Sliding friction

       b. Static friction

       c. Fluid friction

       d. All of the above

10.   The shape of the airplane is like a

        a. Bird

        b. Car

        c. Dog

        d. All

Answers

1.    B

2.    A

3.    A

4.    B

5.    C

6.    D

7.    C

8.    B

9.    D

10. A

1.   Does friction depend on the nature of objects?

2.   Which type of surface produces more friction?

3.   Which type of surface produces less friction?

4.   Which is less sliding friction or static friction?

5.   Why is it difficult to move on a wet marble floor?

6.   What would happen when an object starts moving if there is no friction?

7.   Give two examples where friction is undesirable?

8.   Our hands become warm when we rub them. Why?

9.   Why do we shape aero planes like that of bird?

10.   Write some methods to reduce friction?

11.   Write various types of friction.

12.   What is a fluid friction? Write the factors on which fluid friction depends.