Question

On a smooth plane surface (figure) two block A and B are accelerated up by applying a force 15 N on A. If mass of B is twice that of A, the force on B is

• A. 30 N
• B. 15 N
• C. 10 N
• D. 5 N

Answer 1

Answer: (C)

10 N

Answer 2

 a = $\frac{F}{m + 2m}$ = $\frac{15}{3m}$

2 m : $\xrightarrow { \mathrm { F } _ { \mathrm { C } } } 2 \mathrm {~m}$

F_C = 2 ma

= $2m\left( \frac{15}{3m} \right)$ = 10 N