Question

Two masses of 10 kg and 20 kg respectively are tied together by a massless spring. A force of 200 N is applied on a 20 kg mass as shown in figure. At the instant shown the acceleration of 10 kg mass is $12\text{ }m/{{s}^{2}},$ the acceleration of 20 kg mass is

• A. zero
• B. $10\text{ }m/{{s}^{2}}$
• C. $4\text{ }m/{{s}^{2}}$
• D. $12\text{ }m/{{s}^{2}}$

Answer 1

Answer: (C)

$4\text{ }m/{{s}^{2}}$

Answer 2

Force on the block of 10 kg
$=ma=10\times 12=120N$
The total force applied = 200 N The force acting on block of 20 kg
$=200-120=80\text{ }N$
The acceleration of block of 20 kg
$=\frac{80}{20}=4\,m/{{s}^{2}}$