Answer
The instantaneous rate of energy transfer is $~~900~W$
Work Step by Step
We can find the force on the block:
$F = ma$
$F = (15~kg)(2.0~m/s^2)$
$F = 30~N$
We can find the instantaneous power when the block's speed is $30~m/s$:
$P = F~v$
$P = (30~N)(30~m/s)$
$P = 900~W$
The instantaneous rate of energy transfer is $~~900~W$
