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# work out the root of a unit Watch

1. I have a calculation and the units are square root of 9 km^3 s

what would the answer be ? im thinking 3 km^2 s
2. What are the units?
3. its an algedra equation, I have brought it down to
d = square root of 9 km^3 s

so 9 kilometers^3 per second
4. This really is nonsense gibbyni. Do you want to explain what you are trying to achieve?
5. ok lets say when doing e=mc^2
Mass 1kg
C (speed of light) is 3.0 x 10^8 m s^-1

e = 1 kg x (3.0 x 10^8 m s^-1)^2

e = 1 kg x 9.0 x 10^8 m^2 s^-2

result is 9 x 10^16 kg m^2 s^-2

its the bits about kg m^2 s^-2 that im talking ablout changing, since when the m s^-1 was squared it changed to m^2 s^-2.

So im needing to know what happens to my km^3 s when I find the square roof of my equation.
6. Well, looking at your units should tell you that taking the square root of this gives you an unphysical quantity. So why worry about it?
7. (Original post by gibbyni)
ok lets say when doing e=mc^2
Mass 1kg
C (speed of light) is 3.0 x 10^8 m s^-1

e = 1 kg x (3.0 x 10^8 m s^-1)^2

e = 1 kg x 9.0 x 10^8 m^2 s^-2

result is 9 x 10^16 kg m^2 s^-2

its the bits about kg m^2 s^-2 that im talking ablout changing, since when the m s^-1 was squared it changed to m^2 s^-2.

So im needing to know what happens to my km^3 s when I find the square roof of my equation.
Ok I understand dimensions - I want to know why you think you need to take because, if this is a physics question, you have certainly made a mistake. As Zhen Lin said the answer you obtain is not a physical quantity.

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