Question

In the arrangement shown below, the force with
which 20 kg block pulls 5 kg block is
F= 100 N
5 kg
120 kg
Smooth horizontal surface
(1) 20 N
(2) 25 N
(3) 75 N
(4) 80 N​

Answer 1

i think the answer is 25

Answer 2

The force with which 20 kg block pulls the 5 kg block is 20N

Refer the below diagram of two blocks and a string attachment.

Individual free body diagrams have been drawn below:

String has the same tension because it is incompressible and elastic. (T)

The surface is smooth and the coefficient of friction is zero and there will be no frictional force acting in the free body diagram.

From Newton's second law of motion we know that F = ma

(Force = mass × acceleration)

F = 100 - T

20.a = 100 - T ___(i)

T = 5.a ___(ii)

on solving (i) and (ii)

a = 4 m/s2

Hence T = 5×4 = 20 N