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# Unit of Energy - kJ

## Unit of Energy - kJ

We have in Mathcad 15 and Prime cal and kcal but J and not kJ.

It will be good to have kJ as built-in unit of Energy!

5-Regular Member
 We have in Mathcad 15 and Prime cal and kcal but J and not kJ.It will be good to have kJ as built-in unit of Energy!

Good shout Valery, either implement individual units, or make it easier to add your own to Mathcad.

Mike

19-Tanzanite

It should support all standard prefixes for all units. So if J is defined, so is fJ, nJ, kJ, MJ, TJ, etc

24-Ruby III
 Richard Jackson wrote:It should support all standard prefixes for all units. So if J is defined, so is fJ, nJ, kJ, MJ, TJ, etc

Ok, we can do this in Mathcad: k:=1000 m:=10^-3 M:=10^6 n:=10^-9 etc

and than use kJ MJ nm (k*J M*J n*m) and ALL other units with invisible * sign!

But!

What is the base unit of mass in SI - kg!

What can you say about kkg mkg (k*kg m*kg) etc

No!

We do not use all prefixes with all units: kJ, Gcal etc is OK but kkg, mkg and a lot of others (nkm mmm) are not!

24-Ruby III

A propos.

If we now have in Prime g as a constant (9.81 m*s^-2) it will be good to have g as built-in unit of mass.

(for example we have R as a (gas) constant and R as unit of temperature (rankine)

5-Regular Member
 No!We do not use all prefixes with all units: kJ, Gcal etc is OK but kkg, mkg and a lot of others (nkm mmm) are not!

Good point. When dealing with units such as kg, prefixes are usually not used, but can be denoted by x10^.

Mike

19-Tanzanite

The fact that the base unit is kg is irrelevant. In the case of mass, internally Mathcad has g defined. Therefore it has kg defined. It also knows that the base unit is kg, and will reduce units to that.

I don't understand why you think mmm would occur, even using your line of thinking, because m is the base unit.

19-Tanzanite
 Good point. When dealing with units such as kg, prefixes are usually not used, but can be denoted by x10^.

Because the unit is not kg, it's g. For large masses it's true that we don't usually see Mg, Tg, etc, but for small masses we do see mg, ng, pg, etc. And for large masses, just because it's unconventional doesn't mean it should be forbidden. Mg is a valid SI unit, and if I want to use it then it should be available.

The way to be certain that any valid unit someone wants is available, even if it is unusual (e.g. Mg), is to have all the prefixes defined, and all the base units. In this context "base" means base in terms of nomenclature, not the SI base unit. Mathcad could easily keep track of which is the SI base unit, just as it does now.

5-Regular Member
 Because the unit is not kg, it's g. For large masses it's true that we don't usually see Mg, Tg, etc, but for small masses we do see mg, ng, pg, etc. And for large masses, just because it's unconventional doesn't mean it should be forbidden. Mg is a valid SI unit, and if I want to use it then it should be available.

Mg might be a valid SI unit, but I have never seen it used in Engineering before. As soon as masses reach around 1000kg they are usually described in tonne.

 The way to be certain that any valid unit someone wants is available, even if it is unusual (e.g. Mg), is to have all the prefixes defined, and all the base units. In this context "base" means base in terms of nomenclature, not the SI base unit. Mathcad could easily keep track of which is the SI base unit, just as it does now.

Fully agree.

Mike

19-Tanzanite
 Mg might be a valid SI unit, but I have never seen it used in Engineering before.

I have never seen it used anywhere I don't think there's any rule that says you can't use it though.

5-Regular Member
 I have never seen it used anywhere I don't think there's any rule that says you can't use it though.

Quite right.

Mike

5-Regular Member
 A propos.If we now have in Prime g as a constant (9.81 m*s^-2) it will be good to have g as built-in unit of mass.(for example we have R as a (gas) constant and R as unit of temperature (rankine)

+1

Mike

19-Tanzanite
 A propos.If we now have in Prime g as a constant (9.81 m*s^-2) it will be good to have g as built-in unit of mass.(for example we have R as a (gas) constant and R as unit of temperature (rankine)+1

+1

24-Ruby III
 Richard Jackson wrote:It should support all standard prefixes for all units. So if J is defined, so is fJ, nJ, kJ, MJ, TJ, etc

... klb (base compromise mass unit for Old and New World - kilopound), min (miliinch), din (line=inch/10), dagal (10 gal), etc

19-Tanzanite

OK. Some combinations should not be allowed.

Community Manager
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