Question

Two bodies having the same mass 5kg each
have different surface areas 20m2 and 10m“
in contact with a horizontal plane. If the
coefficient of friction is 0.4, the forces of
friction that come into play when they are in
motion will be in the ratio
1) 1:1 2) 1:2 3) 2:1 4) 1:4​

Answer 1

Explanation:

Normal reaction exerted by plane on each body=N=mg=5g

Friction force exerted by plane on each body=uN=0.4(5g)...(1)

From 1 we can see that friction force does not depend on surface area

Therefore ratio of friction on each body=1

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HOPE THIS HELPS ❤️

Answer 2

HINT: SURFACE AREAS ARE NOT AN IMP. FACTOR IN THIS CASE.

Thus,

(f.f.)1 /(f.f)2 =u1.mg/u2.mg

or, (f.f.)1 /(f.f)2 = 1/1

or, (f.f.)1 : (f.f)2 = 1:1