Page 74 - Genius Kidz Prudence Learning Sc-8

Advantages of Friction Methods adopted for smoothing of surface

(i) Friction exists between our feet and the include :
floor, that's why we are able to walk and (i) Polishing : Polishing of a surface
stand comfortably on the ground. smoothens it. For examples jewels of
(ii) Vehicles can be driven on the roads due to watches are polished so as to hold axles

friction between tyres and the road. between them.
(iii) We are able to write on a paper due to the
friction between pen point and the paper.

(iv) Friction allows us to tie a knot between the
two surfaces say two ropes.

(v) Friction allows us to light up a match stick.
(vi) Friction allows us to sew our clothes.

So, friction is a boon for sure to sustain our Polishing
life.
(ii) Lubrication : Lubrication also reduces
Disadvantages of Friction :
friction. By application of a lubricant
(i) Friction opposes motion so energy is friction between two surfaces is reduced
wasted to overcome the frictional force so because then the surfaces of the two
as to allow the movement of the body. objects do not rub against each other

(ii) Energy applied to overcome friction gets instead lubricated surfaces rub against
converted into heat energy. This heat is each other which have much less friction as
unwanted and unnecessarily raises the compared to original rough surfaces. For
temperature of a body. For example, in the example, “face powder” is sprinkled on
case of a motor, its insulation of windings carom board so as to reduce the friction
gets melted up by heat as a result of which between the striker and the carom board,

motor gets burnt. fans are greased and cycle parts are oiled so
(iii) Since, motors etc run with the help of as to reduce the friction.
electric power. Power consumption of the

electrical appliances is more because of
the energy required to overcome friction.
This increases our electricity bills.
Methods opted to reduce friction :

Friction is directly proportional to the Lubrication to reduce friction
roughness of surface. So, the only way to (iii)Ball and Bearings : As we have already
reduce friction is to make the surface smooth.
discussed that rolling friction is less than

Light takes 13 second to reach the earth from the sun.

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