Physics Help Forum Finding the power used to change phase?

 Thermodynamics and Fluid Mechanics Thermodynamics and Fluid Mechanics Physics Help Forum

 Apr 16th 2019, 12:00 AM #1 Junior Member   Join Date: Apr 2019 Posts: 23 Finding the power used to change phase? I have figured the heat added to the system so far, but can't figure out where to go from here to get the change in internal energy to work out the work(W)? https://imgur.com/a/4SiM6fd It is question number 3 right at the bottom of the photo. Thank you for any help.
 Apr 16th 2019, 12:57 AM #2 Senior Member   Join Date: Apr 2017 Posts: 513 We are told latent heat of evaporation is 2256 KJ/Kg .... 0.3 Kg evaporates so to do that requires 2236 x 0.3 = 676.8KJ But they want the answer in Watts , since the time period is 1 HR (3600secs) then the number of joules is the wattage operating for 3600 secs (1 W is 1J/sec) W x 3600 = 676800 ......W = 188
Apr 16th 2019, 01:18 AM   #3
Junior Member

Join Date: Apr 2019
Posts: 23
 Originally Posted by oz93666 We are told latent heat of evaporation is 2256 KJ/Kg .... 0.3 Kg evaporates so to do that requires 2236 x 0.3 = 676.8KJ But they want the answer in Watts , since the time period is 1 HR (3600secs) then the number of joules is the wattage operating for 3600 secs (1 W is 1J/sec) W x 3600 = 676800 ......W = 188
OOHOH MYYY GOOODD. I LITERALLY DID NOT SEE THE TIME. I need to read better....thank you.

Gah that's something they keep telling us and emphasising all the time. "READ the question". You know what I do? "aahh pfftt, I can read. Lol. Who doesn't read the question properly duh psh" Also me: this

Cheers friend!!!

 Apr 16th 2019, 02:27 AM #4 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 666 Unfit drillers Oz is a very good technician, first rate. He goes to the comet, here is one follower.

 Tags change, finding, phase, power

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