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

[单选题]
Which of the following coulph w rs)oylah:9 ;k6 k(u5kpe,d be a q2lrgfl 7x58n xd;yz) 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 te5w 8zfrs2ew;wof2 h.6qa7kw urms of fundamental units by considering the equations you would use to calculate the derived value. By replacing each term with its unit in the equation, y8a 6 o.ffw2wr; wku52hsw7z qeou 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: $$ \mathrm{kg} \times \mathrm{ms}^{-2} \times \mathrm{ms}^{-1}=\mathrm{kg} \cdot \mathrm{m}^2 \cdot \mathrm{s}^{-3} . $$