Converting Calories to Joules: Uncovering the Correct Conversion Formula

[Quarlep]

Lets suppose we have 2000 kcal and we want to translate it joule.
1 calorie is 4,2 J/gC isn't it so I think it will be 8400000 g m^2/s^2 But my teacher says its 8400000 kg m^2/s^2
Which one is true
Thanks

 

[Quarlep]

Note: Here (4,2 J/gC) J is joule g is grams and C is celcius

 

[jtbell]

1 calorie is 4,2 J/gC isn't it

No, 1 cal = 4.2 J (to one decimal place).

You're thinking of the specific heat of water, which is 4.2 J/(g·°C) = 1 cal/(g·°C).

 

[Quarlep]

Then let me clear Q=mcT and W=mgh so If we takes m we get Q/cT=W/gh If we write the unit form cal cal^-1 g C^-1 C we get g which it grams
and the other side kg m^2 s^-2 s^2 m^-1 m^-1 then we get kg.It does not match.and I think its a problem

 

[jtbell]

You're getting grams for the m from the first equation because you're using the specific heat per gram. Use the specific heat per kilogram instead: 4200 J/(kg·°C).

 

[Quarlep]

Thanks I understan it