Three blocks of masses ` m _ 1 , m _ 2 and m_ 3 ` are connected by mass less string as shown kept on a frictionless table.

They are pulled with a force ` T _ 3 = 40 N. ` If ` m _ 1 = 10 kg, m _ 2 = 6 kg and m _ 3 = 4kg`, the tension ` T _ 2 ` will be

Options

A. 20 N
B. 40 N
C. 10 N
D. 32 N

Answer

D

Explanation

Common acceleration
` a = ( F) /( m _ 1 + m _ 2 + m _ 3 ) `
` a = (40 ) /( 10 + 6 + 4 ) = 2 m//s^2 `
Equation of motion of ` m _ 3 ` is
` T _ 3 - T _ 2 = m _ 3 a, 40 - T_ 2 = 4 xx 2 `
` T _ 2 = 32 N `