Work done by gas expanding with pv=1000 from 1000 to 500 kPa

[bradycat]

A gas expands according to the equation pv=1000. where p is pressure in kPa and v is specific volume m^3/kg. If the gas pressure drops from 1000 to 500kPa, how much work was done by the gas??

Ok I am new to thermo and given a question and can't figure it out.
Do I use net flow work = p2v2-p1v1??
Answer is 693.1 kJ/kg.

or is it w-p delta v?
I am not sure.
Any help or direction would help thanks

 

[grzz]

Start from
work = force x displacement
BUT remember that the force is not constant.