Question

In the arrangement shown in figure, the ends P and Q of an inextensible string move downwards with uniform speed u. Pulleys A and B are fixed. The mass M moves upwards with a speed

• A. $2u\cos \theta$
• B. $u/\cos \theta$
• C. $2u/\cos \theta$
• D. $u\cos \theta$

Answer 1

The correct option is B $u/\cos \theta$

The correct option is B.

Given,

$P$ and $\theta$ are exentissible string $Speed=u,mass=m$

So, The point on the thread just connected to mass m will also have the same velocity,

The component of the velocity along the thread is $v\cos \theta$. It means any point on the thread must be having with speed $v\cos \theta$

$v\cos \theta =u\Rightarrow v=\frac{u}{\cos \theta }$