Question

Two masses of $10$ kg and $20$ kg are connected by a mass less spring as shown in the figure. A force of $200$N acts on the $20$ kg mass. At a certain instant, the acceleration of $10$ kg mass is $12$ $m/s^2$. The acceleration of the $20$ kg mass at that instant is?

• A. $12m/s^2$
• B. $10m/s^2$
• C. $4m/s^2$
• D. None of these

Answer 1

The correct option is C $4m/s^2$

Force acting on 10 kg mass= mass$\times$acceleration=120 N

As acceleration =12 $m/s^2$

So ${\text{Force}}_{Net}$=200-120=80 N

Since Force= mass$\times$acceleration

a$=\frac{\text{Force}}{\text{mass}}=\frac{80}{20}=4m/s^2$