Question

In given figure, find the acceleration (in m/s) of the block B. Assuming pulley is ideal and rope
is massless
A 10kg
20kg B
OON​

Answer 1

Correct Question:

The masses of blocks A and B are 20 kg and 10 kg, respectively. The blocks are at rest on the floor. An upward force F is applied to the pulley. Find the acceleration of the two blocks A and B when F is 124 N.

Assume pulley and rope to be massless.

Solution:

So, let the tension in the string be T.

So, from the FBD , we can say that:

$\therefore \: 2T = 124$

$\implies \: T = 62 \: N$

Now , we can see that the gravitational force on the blocks will be :

On block A:

$\therefore \: mg = 20 \times 10 = 200 \: N$

On block B:

$\therefore \: mg = 0 \times 10 = 100 \: N$

So, the tension is lesser than the weight of the block, hence the block will not move upwards (hence stay on the floor).

So, acceleration of both blocks will be zero.

Hope It Helps.