Help for physics question.

• Zeeeeeee

  4 Oct 08, 13:30

  0.1 kg of steam is passed into 10kg of crushed ice. determine the final temperature of the mixture when it reaches thermal equilibrium. Given that :

  specific heat capacity of water= 4200 J/ kg K

  specific heat capacity of ice = 2100 J/ kg K

  specific heat capacity of steam= 2080 J/ kg K

   , of water = 336000 J/kg

  specifc latent heat of steam= 2260000 J/kg

   

   

• skythewood

  4 Oct 08, 13:40

  transform all steam to water = 2260000 J/kg x 0.1kg
                                                   = 226000J

  cool all the steam water to freezing point = 4200 J/ kg K x 0.1kg x 100K
                                                                        = 42000J

  transform all steam water at freezing point to ice = 336000 J/kg x 0.1kg
                                                                                      = 33600J

   

   

  hence to convert all the steam to ice, = 226000+42000+33600
                                                                  = 301600

  how much ice will melt to convert the steam to ice, = 301600 / 336000 J/kg
                                                                                         = 0.898kg

  hence, there will be 9.202 kg of ice, 0.898kg of water, all at freezing point

• eagle

  4 Oct 08, 16:17

  there's no mention of the initial temperature of the steam and ice

   

  btw, for those who wants practice, I have a few more questions here

  http://examworld.blogspot.com/search/label/O%20lvl%20Phy%3A%20Thermal%20Properties%20of%20Matter

• FirePig

  4 Oct 08, 16:20

  Originally posted by eagle:

  there's no mention of the initial temperature of the steam and ice

  
  assumed to be 100 kelvin difference?

• eagle

  4 Oct 08, 16:23

  Originally posted by FirePig:

  
  assumed to be 100 kelvin difference?

  Not necessary. That's too great an assumption.
  
  O level questions usually have steam greater than 100 degrees and ice colder than 0 degrees in their questions.

  Btw, I was reading through previous posts of Hwk Forum, you mentioned that you earned $50 per hour teaching grp tuition. Can pm me which place is it? :D

• FirePig

  4 Oct 08, 16:32

  Originally posted by eagle:

  Not necessary. That's too great an assumption.
  
  O level questions usually have steam greater than 100 degrees and ice colder than 0 degrees in their questions.

  Btw, I was reading through previous posts of Hwk Forum, you mentioned that you earned $50 per hour teaching grp tuition. Can pm me which place is it? :D

  DId i mention it was $50 per hour? If i did, it was my mistake. It was $50 per lesson. One lesson typically lasts 1.5 hours at a tuition centre in Bukit Batok.

   

  The rate isnt really high since for most graduates, they can earn $25-35 an hour and each lesson usually lasts 2 hours at one go per student.

• eagle

  4 Oct 08, 16:45

  Originally posted by FirePig:

  DId i mention it was $50 per hour? If i did, it was my mistake. It was $50 per lesson. One lesson typically lasts 1.5 hours at a tuition centre in Bukit Batok.

   

  The rate isnt really high since for most graduates, they can earn $25-35 an hour and each lesson usually lasts 2 hours at one go per student.

  Ya, I saw it... was thinking how... haha

  Thanks for the clarifcation... It's actually possible to reach >$50 per hour if u organise your own group :D

• tinuviel07

  4 Oct 08, 16:48

  is that rate high for group? hmmm.. technically group supposed to earn more than 1-on-1 right