Question

The masses of 10 kg and 20 kg respectively are connected by a massless spring as shown in figure. A force of 200 N acts on the 20 kg mass. At the instant shown, the 10 kg mass has acceleration $12m/se{c}^2.$ What is the acceleration of 20 kg mass

• A. $12m/se{c}^2$
• B. $4m/se{c}^2$
• C. $10m/se{c}^2$
• D. $Zero$

Answer 1

The correct option is B $4m/se{c}^2$

As the mass of 10 kg has acceleration $12m/se{c}^2$ therefore it apply 120N force on mass 20kg in a backward direction.
$\therefore$ Net forward force on 20 kg mass = 200 – 120 = 80N
$\therefore Acceleration=\frac{80}{20}=4m/s^2$