Question

If contact force between $2 \,kg$ and $4 \, kg$ is $f_{1}$ newton and between $4 \,kg$ and $6 \,kg$ is $f_{2}$ newton, then find out $\left(f_{1}+f_{2}\right)$.

Answer 1

Mass of system $=2+4+6=12 \,kg$
Now, $24-12=12\, a$
$\Rightarrow a=1\, m / s ^{2}$
System $2\, kg$
$24-f_{1}=2(a)$
$f_{1}=22\, N$
System $6\, kg$
$f_{2}-12=6(a)$
$f_{2}=18\, N$