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

[单选题]
Which of the following could bbmfrzr *bqk:7ysa-2f4le9n8 ca + )hge a unit of po os. a /8m lqz/5+v9 yp(qed/r,iecpycwer?

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 v x4 f:pj8i) zo8roe/(2bf)tb7wujl swritten in terms 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, y4s xu 2p:ti)r)78b(o 8ow/flj bjvefzou 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: $$ \mathrm{kg} \times \mathrm{ms}^{-2} \times \mathrm{ms}^{-1}=\mathrm{kg} \cdot \mathrm{m}^2 \cdot \mathrm{s}^{-3} . $$