Question

Two balls $A$ and $B$ of masses $100gm$ and $250gm$ respectively are connected by a stretched spring of negligible mass and placed on a smooth table. When the balls are released simultaneously the initial acceleration of $B$ is $10cm/s^2$ westward. What is the magnitude and direction of initial acceleration of the ball $A$ ?

• A. $25cm/s^2$ Eastward
• B. $25cm/s^2$ Northward
• C. $25cm/s^2$ Westward
• D. $25cm/s^2$ Southward

Answer 1

The correct option is A $25cm/s^2$ Eastward



As no external force is acting on the masses
${\overrightarrow{F}}_{net}=0$
So ${\overrightarrow{a}}_{COM}=0$
$m_A{\overrightarrow{a}}_A+m_B{\overrightarrow{a}}_B=0$

Considering eastward acceleration as positive, $a_B=-10$
$\Rightarrow 100\times a_1+250(-10)=0$
$a_1=25cm/s^2$ Eastward.