1/29 Work

Question 1

for compression work, what is doing the work and what is the sign

Answer 1

the work is positive since work is being done on the system by the surroundings

Question 2

for expansion work, what is doing the work and what is the sign

Answer 2

the work is negative because the system is doing work on the surroundings

Question 3

what is irreversible work

Answer 3

irreversible work is done all in one step

Question 4

if a piston is slammed rapidly to its final volume in one step, what type of work is it

Answer 4

it is irreversible

Question 5

what is reversible work

Answer 5

work is done infinitesimally slowly

Question 6

in reversible work, what is happening to the external pressure and pressure of the gas

Answer 6

the external pressure and gas pressures are constantly changing, the external pressure is infinitesimally larger than the gas pressure

Question 7

in the derivation of the irreversible work equation, why can we assume the pressure is constant and pull it out of the equation

Answer 7

we assume it is constant because the work is done with one big external pressure

Question 8

for reversible work, why can we exchange the Pexternal for the Pgas

Answer 8

the external pressure is infinitesimally larger than the gas pressure, but it is essentially equal to it

Question 9

under what conditions can we use the reversible work equation

Answer 9

when the temperature is constant, isothermal

Question 10

if the volume is constant, what is the work

Answer 10

it is zero

Question 11

when dealing with a PV diagram, how do we calculate the work

Answer 11

treat the two paths as different work equations and subtract the second path from the first