Question

In which of the following cases is the contact force between $A$ and $B$ is maximum. If mass of each block is $1\text{kg}$ and assume all surfaces to be smooth :-

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

Case $A$
Net acceleration of masses
$a=\frac{30}{2}=15{\text{m/s}}^2$

FBD of block B:Normal force $N=1\times 15=15N$

Case B

FBD of Block A:$N=10+2=12N$

Case C-

FBD of Block A:$N-10=1\times 2$
$N=12N$


Case D-
FBD of Block A-
$N=1\times 10=10N$