question_answer

A 2 kg mass starts from rest on an inclined smooth surface with inclination 30o and length 2 m.  How much will it travel before coming to rest on a frictional surface with frictional coefficient of 0.25                           [UPSEAT 2003]

A)             4 m     

B)             6 m

C)             8 m     

D)             2 m

Correct Answer: A

Solution :

                         \[{{v}^{2}}={{u}^{2}}+2as=0+2\times g\sin 30\]\[\times 2\] Þ \[v=\sqrt{20}\]             Let it travel distance ?S? before coming to rest             \[S=\frac{{{v}^{2}}}{2\mu g}=\frac{20}{2\times 0.25\times 10}=4m\]