Q.
Two blocks $A$ and $B$ are connected by a massless string (shown in figure). A force of 30 N is applied on block $B$. The distance travelled by centre of mass in 2 s starting from rest is
A) 1 m
B) 2 m
C) 3 m
D) None of these
Explanation
(b) The acceleration of centre of mass is
$a_{CM} = \frac{F}{m_{A} + m_{B}}$
$= \frac{30}{10 + 20} = 1ms^{- 2}$
$\therefore\ s\text{=}\frac{1}{2}a_{CM}t^{2} = \frac{1}{2} \times 1 \times 2^{2} = 2$ m
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.