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Homework Help: Having problems with my physics class

  1. Apr 17, 2008 #1
    The teacher doesn't go slow enough, and make sure you understand the material.. What he goes over in class isn't on the test or homework, so im close to failing. I was hoping to get some help. I have an online test tomorrow (friday) and was hoping i could post some questions, and maybe get some help on them.. Here is one of the questions that might be on it.

    How many calories of heat are required to convert .250 kg of ice at 0 °C into steam at 100 °C? Solve this problem in steps:

    How much heat is required to melt the ice and produce water at 0 °C?

    How much heat is required to raise the temperature of the water to 100 °C?

    How much heat is required to boil the 100 °C water into water vapor (steam) at 100 °C?

    What is the total amount of heat that was added to the original ice at 0°C to turn it into steam at 100 °C?

    And the answers must be in Kcal... Thats a question on the homework.. and i dont even understand that.. any body lend some help?
  2. jcsd
  3. Apr 17, 2008 #2
    Hey, welcome to pf. Before I start helping you I would like you to tell you a few things about science that I have learnt from past experience, firstly, answering science questions comes down to one thing, confidence. The only way you can improve is to tackle as many science problems as you can so that you can gain the confidence you need to tackle the harder problems, but since time is nearly up for you I would say it is too late to utilise this piece of advise for now, but keep it in mind for the future ;). Secondly, science teachers will teach you the foundations of a subject, they will give you definitions of key words and the basic formula's to solve problems in that area, but it is up to YOU to understand these formula's so you are capable of rearranging them to calculate whatever value you are looking for. Now, I do not know what your teacher has taught you but I am sure he has taught you the definition of a calorie, which is:

    calorie is the amount of energy(usually heat energy) required to raise the temperature of one gram of water by 1 °C.

    Now from this definition, I believe you can tackle most of the problems above ;)
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