Physics

Problem

Which expression gives the average power delivered to a system during a time interval

\Delta t

in which its mechanical energy changes by

\Delta E

? a)

P_{\text{avg}}=\dfrac{|\Delta E|}{\Delta t}

P_{\text{avg}}=\dfrac{E_i+E_f}{2\,\Delta t}

P_{\text{avg}}=\dfrac{\Delta E}{\Delta t}

P_{\text{avg}}=\dfrac{2\,\Delta E}{\Delta t}