Question

A $4kg$ box and a $5kg$ box are next to each other. A child pushes from the $4kg$ end with a force of $9N$.
What is the acceleration of the $5kg$ mass?
There is no friction acting on the blocks.

• A. $1m/s^2$
• B. $1.25m/s^2$
• C. $1.8m/s^2$
• D. $2m/s^2$
• E. $2.25m/s^2$

Answer 1

Answer: (A)

$1m/s^2$

Net external force $F=9$ N

Total mass of the system $M=4+5=9$ kg

Thus acceleration of the system $a=\frac{9}{9}=1$ $m/s^2$

$\therefore$ Acceleration of 5 kg mass $a^{\prime }=a=1$ $m/s^2$