Question

Two masses of $10\,kg$ and $5\,kg$ are suspended from a rigid support as shown in figure. The system is pulled down with a force of $150\, N$ attached to the lower mass. The string attached to the support breaks and the system accelerates downwards. If the downward force continues to act, the acceleration of the system is

• A. $20\,ms^{-1}$
• B. $10\,ms^{-1}$
• C. $5\,ms^{-2}$
• D. $zero$

Answer 1

Answer: (A)

$20\,ms^{-1}$

Answer 2

Total force on the system will be weight of the system + 150 N = 300 N. Hence acceleration of the system when force continues to act will be 300 N/15 kg = 20 m $s^{-2}$ = a (say). Tension in the string will be 10 $\times$ a = T + 10 $\times$ g, which gives T= 100 N