Question

a watt (w) is equal to
o a kg x m/s^2
o b kg x m^2/s^3
o c kg x m^2/s^2
o d m/s^2

Explanation:

Step1: Recall power formula

Power $P=\frac{W}{t}$, where work $W = F\times d$ (Force $\times$ distance), and force $F=ma$ (mass $\times$ acceleration).

Step2: Substitute units

The unit of mass $m$ is kg, unit of acceleration $a$ is $m/s^{2}$, unit of distance $d$ is m and unit of time $t$ is s. First, $F = ma$ has unit $kg\times m/s^{2}$, then $W=F\times d$ has unit $(kg\times m/s^{2})\times m=kg\times m^{2}/s^{2}$. And $P = \frac{W}{t}$, so the unit of power is $\frac{kg\times m^{2}/s^{2}}{s}=kg\times m^{2}/s^{3}$.

Answer:

B. $kg\times m^{2}/s^{3}$