What is the acceleration of the block and trolley system shown in a Fig.(a), if the coefficient of kinetic friction between the trolley and the surface is 0.04? What is the tension in the string? (Take g =` 10 m s^(-2)` ). Neglect the mass of the string.

Explanation

Free body diagram of the block
` 30-T = 3a`
Free body diagram of the trolley
` T- f_(k) = 20 a`
where ` f_k = mu _k N = 0.04 xx 20 xx 10=- 8 N`
solving (1) & (2) , a ` = 0.96 m//s^2 and T = 27.2 N`