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

[单选题]
Which of the followingk2b 6 -hxukl d-ia(5je coul1u q:g01 sv6losz;xgntv wkf n 83,1bdd 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 ofshe() h,2wt kx fundamental units by considering the equations you would use to calculate the derived value. By replacing each term with its unitw 2xs,)k(e hth in the equation, you can obtain the new 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: $$ \mathrm{kg} \times \mathrm{ms}^{-2} \times \mathrm{ms}^{-1}=\mathrm{kg} \cdot \mathrm{m}^2 \cdot \mathrm{s}^{-3} . $$