Question

In the figure, a force $F=20\text{N}$ is applied on block $\text{A}$. What would be the acceleration of the block $\text{B}$ after $10$ seconds from the start. Assume all surfaces are smooth.

• A. $\frac{10}{6}{\text{m/s}}^2$
• B. $2{\text{m/s}}^2$
• C. zero
• D. cannot be calculated

Answer 1

The correct option is C zero

Since all surfaces are smooth, the contact force between $\text{A}$ and $\text{B}$ is the normal reaction only which is vertical, no horizontal force acts on $\text{B}$. Hence its acceleration $a_B=0$.