Question

why work done by expansion of gas is negative?

Answer 1

in order to do work and expand, a gas must "use" some of its energy to push the walls of the container and do the actual expansion. The negative sign simply implies the loss of energy by the system in doing the work.

Answer 2

ok thnx then what is the significance of the formula \[W=PdV\]? acc to this workdone should be positive since dV is positive fo expansion

Answer 3

its just sign convention
in chemistry it is negative
in physics it is positive

Answer 4

ok but why ? is there nothing behind it?

Answer 5

i think concept should be same

Answer 6

no buddy again its just sign convention
decided by some scientists

Answer 7

ok thnx

Answer 8

no problem
exams in one month
wish me luck

Answer 9

gud luck

Answer 10

thanks

Answer 11

wlcm

Answer 12

the formula is \(w=\underbrace{\color{red}-}P_{Ext}\Delta V\)
negative sign

Answer 13

why pext?

Answer 14

external pressure

Answer 15

ok thnx