1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How much does the temperature of a river rise in going over 30 m?

  1. Aug 13, 2014 #1
    1. The problem statement, all variables and given/known data
    Assuming no heat is transferred to or from the surroundings, how much does the temperature of a river rise in going over a 30 m falls? (assume the velocity of the water is the same above and below the falls)


    2. Relevant equations
    Δl = αlΔT


    3. The attempt at a solution
    H = 0 and l = 30. I do not know where to go from there. I also do not know alpha.
     
  2. jcsd
  3. Aug 13, 2014 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    I presume that by "assume the velocity of the water is the same above and below the falls" you mean after that part of its energy has been turned into heat by the turbulence and contact with the rocks and bottom?

    What is the potential energy of, say, 1 kg of water 30 ft m above the bottom of the falls? What is the increase in its kinetic energy at the bottom? What temperature difference does that energy convert to?
     
  4. Aug 13, 2014 #3
    So I calculated the potential energy to be 294 Joules. So would the increase in kinetic energy equal 30?
     
  5. Aug 13, 2014 #4
    No. The decrease in potential energy would be equal to the increase in kinetic energy. If all this kinetic energy were converted to heat, how much would the temperature of the 1 kg of water rise?

    Chet
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: How much does the temperature of a river rise in going over 30 m?
  1. How high does it go? (Replies: 22)

Loading...