A body is mass 20 kg is moving on a rough horizontal plane. A block of mass 3 kg is connected to the 20 kg mass by a string of negligible mass through a smooth pulley as shown in the below figure. The tension in the string is 27 N. The coefficient of kinetic friction between the heavier mass and the surface is `(g = 10 m //s^(2))`

Options

A. 0.025
B. 0.035
C. 0.35
D. 0.25

Answer

b

Explanation

Given, tension in string (T) = 2/N
Mass (m) = 3kg
let acceleration of the block be a.
3g - t = me
`implies 10 xx 3 - 27 = 3a`
`implies 30 - 27 = 3a`
`implies a = (3)/(3) = 1 m//s^(2)`
for the body, we have,
`27 - mu 20g = 20a`
`implies 27 - mu xx 20 xx 10 = 20 xx 1`
`implies 27 - 200 mu = 20`
`implies 200 mu = 27 - 20`
`:.` Coefficient of kinetic friction,
`mu = (7)/(200) = 0.035`
`:.` Coefficient of kinetic friction is 0.035