Question

Two blocks of mass $4kg$ and $2kg$ are attached by an inextensible light string as shown in figure. Both the blocks are pulled vertically upwards by a force $F=120N$. Find the acceleration of the blocks.

• A. $10$
• B. $30$
• C. $60$
• D. $40$

Answer 1

The correct option is A $10$

Let $a$ be the acceleration of the blocks and $T$ the tension in the string as shown in the figure.
Taking the two blocks and the string as the system shown in figure
Using we get $\Sigma F_y=m{a}_y,$
$F-4g-2g=(4+2)a$
or $120-40-20=6a$
or $60=6a$
$\therefore a=10m/s^2$