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DAV CLASS 8 CHAPTER 5 SCIENCE SOLTION-friction

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Hello Students, Toady we are starting our Class 8 Science Chapter-5 friction of DAV Book 2021. If You are in class 8 and looking for Class 8 Science Chapter- Chapter-5 friction CBSE/DAV Book Solution 2021. Then you are absolutely at the right place of knowledge decode

Class 8 Science Chapter 1 : The Cell- Its Structure and Functions

class 8 science chapter 2 : Microorganisms : friends or foes

class 8 science chapter 3 : Metals and Non-metals

class 8 science chapter 4 : force and pressure

This Post Contains All The Exercises of Chapter 5 Science Of Class 8 .

A.Fill In The Blanks.

B.Math The Following.

C.Tick(√) The Correct Option

D.Answer The Following Questions in Brief

E.Answer The Following Questions

SOLUTION

A. FILL IN THE BLANKS.

friction always opposes any relative motion between the two surfaces that are in contact with each other.
static friction is always greater than sliding friction.
sportsmen use shoes , fitted with spikes , to increase friction between their shoes and the ground.
sprinkling of talcum powder , on the carrom board , helps to reduce friction.
frictional force , on an oject moving in a fluid , depend on its shape and speed.
the shape of an aeroplane is streamlined to reduce , the effects of friction , due to air.

B. STATE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

When a body slids over smooth and wet surfaces, the amount of interlocking of irregularities, of the two surfaces in contact , increases. false
If a car moves eastwards , the force of friction acts southwards. false
Friction depende on how hard the two surfaces press against each other. true
the sole of shoes and the tyres of the vehicles are treaded to decrease the effects of friction. false
Lubricants can be liquids, semi-solids or solids. true
friction can be increased by using ball bearings between the moving parts of machines. false
fluid friction can be minimised by giving suitable shapes to the objects moving through the fluid. true

C. TICK THE CORRET OPTION.

Suppose your writing desk is tilted to a position where a book kept on it just starts sliding down. the figure, showing the correct direction of frictional force acting on it, is- (d)
two boys are applying oppositevly, direced , and equal in magnitude , force on a box . in such a case , the force of friction , that would exist between the lower end of the box and the ground , would be called- (b)static friction
The energy,’used up’ in overcoming friction gets converted mainly into- (b)heat energy
Rahul rolls a ball on a wooden surface . The ball covers a certain distance before coming to rest . To make the same ball cover a longer distance, before coming to rest , rahul should- (c)sprinkle talcum powder on the wooden surface.
A block is sliding on a horizontal surface .the force of friction between the two can be increased by- (d)by putting a second identical block on top of the given block