question_answer

Two bodies having the same mass 2 kg each, have different surface areas \[50{{m}^{2}}\]and \[100{{m}^{2}}\]in contact with a horizontal plane. If the coefficient of friction is 0.2. the forces of friction that come into play when they are in motion will be in the ratio:

A)  1 : 1                                      

B)  1 : 2

C)  2 : 1                                      

D)  1 : 4

Correct Answer: A

Solution :

                 Force of friction does not depend upon the surface area of contact bodies. \[f-f={{M}_{B}}a\]                                           ?(i) \[f={{M}_{A}}a\]                                              ?(ii) From relations (i) and (ii) it is clear that force of friction does not depend upon area.