Answer
The instantaneous power at the end of the three second interval is $~~66.7~W$
Work Step by Step
We can find the acceleration:
$v_f = v_i+at$
$a = \frac{v_f-v_i}{t}$
$a = \frac{10~m/s-0}{3.0~s}$
$a = 3.333~m/s^2$
We can find the magnitude of the force:
$F = ma$
$F = (2.0~kg)(3.333~m/s^2)$
$F = 6.67~N$
We can find the instantaneous power at the end of the three second interval:
$P = F~v$
$P = (6.67~N)(10~m/s)$
$P = 66.7~W$
The instantaneous power at the end of the three second interval is $~~66.7~W$
