Page 76 - Genius Kidz Prudence Learning Sc-8

(c) Limiting friction is the:
(i) maximum value of static friction (ii) maximum value of rolling friction

(iii) maximum value of fluid friction (iv) maximum value of sliding friction
(d) Cars have a streamlined body to _____________ friction.

(i) increase (ii) reduce (iii) both (i) and (ii) (iv) None of these

2. Fill in the blanks.
(a) Friction acts in the _______________ direction to that of motion.
(b) Cause of friction is _______________ .

(c) Static friction is the friction between two _______________ objects.

3. Match the columns.
Column A Column B

(a) Limiting friction (i) Viscous fluids
(b) Rolling friction (ii) Between rolling objects
(c) More fluid friction (iii) Between static objects

(d) Static friction (iv) Between sliding surfaces
(e) Sliding friction (v) Maximum friction

4. Mark the statements as True /False .
(a) Lubrication is used to increase the friction between two objects.

(b) Static friction > sliding friction > rolling friction.
(c) Light energy is produced while overcoming friction.

5. Very Short answer type questions.
(a) Define friction. What type of force is it?

(b) Soap solution is used to loosen up ring in the finger. What does this soap solution do?
(c) Why does a baller rub his hands with the dust or on ground prior to balling?

6. Short answer type questions.

(a) Give two examples where friction acts as a boon for us.
(b) Give three examples where friction acts as an evil for us.
(c) Why is a boat always made streamlined?

(d) How does the surface area of a body affect friction ?

7. Long answer type questions.
(a) What is friction? Discuss it in detail with its types and causes.

(b) What are the different methods that can be used to reduce friction?
(c) Write short notes on :
(i) Rolling friction (ii) Fluid friction (iii) Sliding friction (iv) Static friction

(d) Why is friction necessary ? Give some examples where increase in friction is required.

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