Question

A 20 -kg block is placed on a top of a 50-kg block as shown in fig., A (50 kg) horizontal force F acting on A causes an acceleration of $3m{s}^{-2}$ to A and $2m{s}^{-2}$ to B(20 kg) as shown in the figure. For this situation, mark out the correct statement(s)

• A. The friction force between A and B is 40 N.
  
• B. The net force acting on A is 150 N.
  
• C. The value of F is 190 N.
• D. The value of F is 150 N.
  

Answer 1

Answer: (A), (B), (C)

The correct options are
A The friction force between A and B is 40 N.
B The net force acting on A is 150 N.
C

The value of F is 190 N.

Let f be the friction force on both the block A and B as shown in the FBD diagram.

A block has an acceleration of $3m{s}^{-2}$

$F-f=50\times 3$ eq(1)..

B block has an acceleration of $2m{s}^{-2}$

$f=20\times 2$ eq(2)...

on solving eq(1) and eq(2).

$f=40N$

$F=190N$

the total force acting on the A block is

$F-f=190-40=150N.$

Hence A,B and C is correct option.