Question

A block of mass $1$ $kg$ starts moving with constant acceleration $a=4m/s^2.$. Find the average power of the net force in a time interval from $t=0$ to $t=2s$.

• A. $16W$
• B. $1.6W$
• C. $15W$
• D. $1.5W$

Answer 1

The correct option is A $16W$

Velocity of an object after time $t$ is given by $v=at$

Average power from time $t_1$ to $t_2$

$=\frac{{\int }_{t_1}^{t_2}Fvdt}{{\int }_{t_1}^{t_2}dt}$

$=\frac{{\int }_0^t\left(ma\right)\left(at\right)dt}{{\int }_0^{t}dt}$

$=m{a}^2\frac{t}{2}$

$=1\times 4^2\times \frac{2}{2}W$

$=16W$