Question

A 100 w lightbulb is place in a cylinder equipped with a moveable piston. The ligshtbulb is turned on for 0.015 hours, and the assembly expands from initial volume of 0.85 L to a final volume of 5.88 L against an external pressure of 1.0 atm. Use the wattage of the lightbulb and the time it is on to calculate delta E in joules (assume that the cylinder and lightbulb assembly is the system and assume two significant figures). calculate w and q..

Answer 1

work = -pdV = -p(Vfinal - Vinitial)
Convert 100 w to watt*sec = joules and that will be q
dE = q+w

Answer 2

w=500
q=291
dE = 791