Thermal Physics> I had observed that in Chemistry Work don...

I had observed that in Chemistry Work done by the system is Negative...., Where as in Physics it it Positive. Please explain which is correct?

S RAMYA , 8 Years ago

Grade 11

2 Answers

Gundeep Singh

Last Activity: 8 Years ago

It is just a convention. If you are taking Work done by system -ve then equation of First law of thermodynamics is written as dQ +dW =dU. If u take work done +ve then it is dQ - dW = dU. U can see that the above two equations give the same result by following their respective sign convention.

Approved

Umakant biswal

Last Activity: 8 Years ago

@ ramya
this is one of the brilliant ques , that is beacuse chemistry and phy are dealing with diffrent thing .,
in chemistry we want to know how usefull a chemical is , . therefore , if it does work , then it loses energy inside it . that makes it less usefull . therefore , work done by chemical is -ve .
in physics , we check how usefull a system is . the measure of usefullness of a system is besically how much energy it can supply us , the more work it does , the more energy it gives us .
therefore , work is +ve in physics .
phy is abt what we can do with stuff , and in chemi what the stuff can do ..
HOPE U UNDERSTOOD THAT .
ALL THE BEST ..

Approved