In physics class, we write the first law of thermodynamics as $\mathrm dU =\mathrm dQ - \mathrm dW$ and in the physical chemistry class, we write the same law as $\mathrm dU =\mathrm dQ + \mathrm dW$.
The reason being the sign convention is different in both the cases.
In physics we take work done by the system as positive and in chemistry work done on the system.
I realize that this does not cause any change in the actual law of nature but I just want to know why we have different sign conventions. Wouldn't just one convention make life easier?
Is there a historical reason? Or is this is to differentiate between subjects?