Question

Two forces of $6N$ and $3N$ are acting on the two blocks of masses $2kg$ and $1kg$ respectively kept on friction less horizontal floor. The force exerted on $2kg$ block by $1kg$ block is:

• A. $1N$
• B. $2N$
• C. $4N$
• D. $5N$

Answer 1

The correct option is C $4N$

Let F be force exerted on $2kg$ block by $1kg$ block,

So Free body diagram:

For 2kg block,

$6-F=2\times a---\left(1\right)$

where a is the acceleration of two blocks

For $1kg$ block

$F-3=1\times a\Rightarrow a=F-3$

Put this value in equation (1)

$6-F=2\times (F-3)\Rightarrow 3F=12\Rightarrow F=4N$