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# Si units confusion

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1. Why is it that for velocity the units are ms ^-1 but for density it's just kg m3 , why is it not just kg m3 ^-1. ??
2. (Original post by HG1)
Why is it that for velocity the units are ms ^-1 but for density it's just kg m3 , why is it not just kg m3 ^-1. ??
The (SI) unit of density are .
3. it is kgm-3 isn't it?
4. (Original post by HG1)
Why is it that for velocity the units are ms ^-1 but for density it's just kg m3 , why is it not just kg m3 ^-1. ??
Velocity is metres per second, so m/s, which is the same as m (*) s^-1.

Density is mass per unit volume, so it's kg / m^3, which is the same as kgm^-3.

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