Question

Consider the situation shown in figure. Both the pulleys and the string are light and all the surfaces are frictionless. Find the tension in the string.

Answer 1

Clearly from the figure,

for block of mass "M"

$Mg-T=Ma$ ...........(i)

from block of mass "2M"

$2T=2M\left(\frac{a}{2}\right)$ ........(ii)

sustitue value of $a$ from equation (i), we get

$2T=2M\left(\frac{Mg-T}{2M}\right)$

$2T=Mg-T$

hence,

$T=\frac{Mg}{3}$