a. Friction opposes the relative motion between two surfaces in contact.
b. Friction is a necessary evil.
c. Irregularities between two surface interlocks to produce friction
d. Friction depends on the nature of the surface in contact
e. Sliding friction is more than static friction
f. Friction produces heat
g. The sole of the shoes and tyres of the treaded to reduce friction
h. Rolling friction is smaller than the sliding friction..
a. Sliding Friction
c. Rolling Friction
d. Static Friction
a. Why it is difficult to move on a wet marble surface
b. why our hands become warmer when we run them
c. Why do we shape aeroplanes like that of a bird
d. How lubricant help in reducing friction
e. The handle of a cricket bat or a badminton racquet is usually rough. Explain the reason.?
a. It has less friction,So it becomes difficult to move on
b. When we rub our hand with each other, friction arises between the two hands. The friction produces heat and this heat makes our hand warmer.
c. Aeroplanes are streamlined like bird to reduce frictional force exerted by air. and not to lose energy
d. Lubricant fills the irregularities present on the surface and forms a thin layer between the surface in contact. This results in replacing the contact between the two hard surfaces with the contact between hard surface and lubricant.This reduces friction
e. To increase friction between handle of the bat and hands, to have a better grip
Fill in the blanks
a. Frictional force is an example of __________.
b. Friction can never be entirely __________.
c. SI unit of friction force is __________.
d. _______ is a device used for measuring the force acting on an object.
e. Direction of force of friction is always __________ to the direction of motion.
g. Substance called ___________ are used to reduce friction Solution
a. non-contact force
Multiple Choice Questions
1. A ball rolling on the ground slows down and finally stops because
(b) less force applied
(d) none of the above
2. A boy rolls a rubber ball on a wooden surface. The ball travels a short distance before coming to rest. To make the same ball travel longer distance before coming to rest, he may
(a) spread a carpet on the wooden surface.
(b) cover the ball with a piece of cloth.
(c) sprinkle talcum powder on the wooden surface.
(d) sprinkle sand on the wooden surface.
3. Which of the following is an example of a non-contact force?
(a) The force exerted by us to lift a bucket
(b) push a stationary car
(c) The force exerted by magnets
(d) Force due to friction
4. The coefficient of friction between the two surfaces depends on
(a) Nature of the surface in contact
(b) Mass of the two bodies in contact
(c) Applied force
(d) Normal contact force between the surface
5. Which one of the following forces is a contact force?
(a) force of gravity
(b) magnetic force
(c) force of friction
(d) electrostatic force
6. Force of friction depends on
(a) Smoothness of the surface
(b) Roughness of the surface
(c) Inclination of the surface
(d) All the above
7. In a large commercial complex there are four ways to reach the main road. One of the path has loose soil, the second is laid with polished marble, the third is laid with bricks and the fourth has gravel surface. It is raining heavily and Paheli wishes to reach the main road. The path on which she is least likely to slip is
(a) loose soil.
(b) polished marble.
8. Force are acting on the body as shown below
The body is at rest due to friction. The friction force is
(a) 50 N from right to left
(b) 50 N from left to right
(c) 10 N from right to left<
(d) 10 N from left to right
9. The use of lubricants makes the surface
(d)None of the above
10.An irregular surface will have
(a) Zero Friction
(b) Lesser friction
(c) Greater friction
1. (c) friction
2. (c) sprinkle talcum powder on the wooden surface.
3. (c) The force exerted by magnets
4. (a) Nature of the surface in contact
5. (c) force of friction
6. (d) All the above
7. (d) gravel.
8. (b) 50 N from left to right
10. (c) Greater friction
This Friction Class 8 Worksheet is prepared keeping in mind the latest syllabus of CBSE . This has been designed in a way to improve the academic performance of the students. If you find mistakes , please do provide the feedback on the mail.