Kognity IB Physics A.0 Measurements & Uncertainty (id: 4a1233956)

[单选题]
Which of the following could 9)/ou32x1rd fdsn lgnb;vfbp dv 5.k;be a unit of power?

A. $kg \cdot m \cdot s^{-2}$
B. $kg \cdot m^2 \cdot s^{-1}$
C. $kg \cdot m^2 \cdot s^{-2}$
D. $kg \cdot m^2 \cdot s^{-3}$


参考答案:  D


本题详细解析:
All derived units can be written in terms of 0tvnu;an3h c2f mg 5(xfundamental units by considering the equations you would use to calculate the derived value. By replacing each term with its unit in the equation, you can obtain the newn2v;chn5fa u 0x3m t(g unit. For example: $$ P=F v $$ where $P$ is power, $F$ is force and $v$ is velocity. In turn: $$ F=m a $$ where $m$ is mass and $a$ is acceleration. So we could write: $$ P=m a \times v $$ and the unit of power in terms of fundamental units must then be: $$ \mathrm{kg} \times \mathrm{ms}^{-2} \times \mathrm{ms}^{-1}=\mathrm{kg} \cdot \mathrm{m}^2 \cdot \mathrm{s}^{-3} . $$