Question

Two mass A and B each of mass M are fixed together by a massless spring A force F acts on the mass B as shown in figure. At the instant shown, the mass A has acceleration a. What is the acceleration of mass B ?

• A. $\left(\frac{F}{M}\right)-a$
• B. $a$
• C. $-a$
• D. $\left(\frac{F}{M}\right)$

Answer 1

The correct option is A $\left(\frac{F}{M}\right)-a$

Here, the two masses are not tied by inextensible string. So, acceleration in different blocks will be different.
Net force on block A = Ma
Remaining force on B = F - Ma
Acceleration of block $B=\frac{F-Ma}{M}=\left(\frac{F}{M}\right)-a$