Question

Find the force of interaction between $3kg$ and $2kg$ (Assume surfaces are frictionless )

• A. $2N$
• B. $3N$
• C. $8.6N$
• D. $5N$

Answer 1

The correct option is C $8.6N$

Considering horizontal direction motion, net horizontal force on the combined system is as shown in figure.
Net force on ($3kg\text{and}2kg$) as system is
$F_{net}=6N$ to the left
Hence,
$a=\frac{F}{m}=\frac{6}{5}=1.2m/s^2$

FBD for $3kg$ block,

$N_1-5=ma=3\times 1.2$
$N_1=5+3.6=8.6N$