Question

A man pulls a 20 kg mass, slowly upwards with the help of light string passing over a frictionless pulley as shown in figure. The normal reaction by floor on the feet of man is (g 10 m/s)​

Answer 1

Given:

A man pulls a 20 kg mass, slowly upwards with the help of light string passing over a frictionless pulley as shown in figure.

To find:

The normal reaction by floor on the feet of man is ?

Calculation:

Since the question says that the man slowly pulls the pulley upwards , we can assume that at each step the pulley is stationary.

In that case , the block is experiencing a tension (in the string) upwards equal to its weight.

$\therefore \: T = 20g \: \: \: \: \: ......(1)$

Now, from the FREE-BODY DIAGRAM of the man, we can say that:

• His weight is acting downwards.

• The tension (in string) is acting upwards.

• The normal reaction on his foot is upwards.

$\therefore \: Mg - T = N$

$\implies\: N = 50g - 20g$

$\implies\: N =30g$

$\implies\: N =30 \times 10$

$\implies\: N =300 \: Newton$

So, the normal reaction on foot is 300 N.