Question

For the arrangement given below, what should be the value of mass M such that the system remains stationary? [Assuming all surfaces to be smooth and strings to be light].

• A. Zero
• B. 10 kg
• C. 15 kg
• D. 5 kg

Answer 1

The correct option is A Zero

Let T be the tension in the string.

For the system to remain stationary:
$Mg–T=M\times a=0$
$\Rightarrow Mg=T$ …..(i)


For the blocks of mass 10 kg and 5 kg as a system:
T = (10 + 5)a
$\Rightarrow T=15\times 0$
$\Rightarrow T=0$ …..(ii)

Putting the value of T = 0 in (i), we get:
$Mg=0$
$\Rightarrow M=0$
Hence, the correct answer is option (1).