Unit Conversion Troubleshooting: Identifying and Correcting Common Errors

[badtwistoffate]

I have 3 unit conversions and they are not coming out right... what am I doing wrong if you can spot it:
1)1.64ly/min to SI Units:
1ly/min=697.5W/m^2
1144.6W/m^2 but how do you get it with just the oringinal SI units...


2)2.3E27carats/parsec^3 to SI:
2.3E27carats/parsec^3 * (1kg/.0002carats) *( 1 parsec^3/2.938e49 m^3) = 3.91E-19 but is nothing like what google says !


3)642 furlongs per fortnight to SI:
642 furlongs/fortnight * (201.2m/1furlong)*(1/[24*60*60])*(201.2m/1furlong)=.107m/s?

 

[Pengwuino]

Wait, light years/min? That's a unit of velocity and W/m^2 is a unit of intensity.

 

[badtwistoffate]

langleys/min

 

[assyrian_77]

You want the units to be basic SI-units? Well, Watt is J/s and Joule is Nm and Newton is kg m/s^2.

You calculated the second one wrong. I got 1.566*10^(-26) kg/m^3. Pay attention to what you do when you change units. Remember that 1 carat = 0.0002 kg, not 1kg = 0.0002 carat.

 

[physicsprasanna]

642 furlongs per fortnight to SI:
642 furlongs/fortnight * (201.2m/1furlong)*(1/[24*60*60])*(201.2m/1furlong)=.107m/s?

That's just one day, not a fortnight.

And why twice 201.2m/1 furlong?