If the unit of mass, length and time be each doubled, then the unit of power remain the same.
Explanation —
The dimension of power is $\left[M L^{2} T ^{-3}\right.$ ]
$\therefore \frac{ U _{2}}{ U _{1}}$ $=\left[\frac{ M _{2}}{ M _{1}}\right]\left[\frac{ L _{2}}{ L _{1}}\right]^{2}\left[\frac{ T _{2}}{ T _{1}}\right]^{-3}=\left[\frac{2 M _{1}}{ M _{1}}\right]\left[\frac{2 L _{1}}{ L _{1}}\right]^{2}\left[\frac{2 T _{1}}{ T _{1}}\right]^{-3}$
$=2 \times 2^{2} \times 2^{-3}=1 \quad \therefore U _{2}= U _{1}$
