Three blocks with masses $m, 2 m$ and $3 m$ are connected by strings, as shown in the figure. After an…
Three blocks with masses $m, 2 m$ and $3 m$ are connected by strings, as shown in the figure. After an upward force $F$ is applied on block $m$, the masses move upward at constant speed $v$. What is the net force on the block of mass $2 m ?$
Zero
$2 \mathrm{mg}$
$3 \mathrm{mg}$
$6 \mathrm{mg}$
Solution
Since all the blocks are moving with constant velocity, then the net force on the all blacks will be zero.
