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  1. I

    Shear Stress due to Laminar flow

    Homework Statement Oil of Density 888kg/m^3 and viscosity 0.8Pa*s is flowing in a horizontal pipe of diameter 0.15m. The local flow velocity at the centerline is 10m/s. find the shear stress exerted by the oil on the wall of the pipe. Homework Equations tau = -eta*(dv/dy) The...
  2. I

    Hess's Law problem

    roughly speaking I integrated the C_p function of Fe2O3 - hematite from 298 to 1200. I really integrated it three times, because hematite has 3 states in this temperature range, and the C_p function for each state is different.
  3. I

    Hess's Law problem

    So I'm taking Thermodynamics I in university. I'm just doing the homework now, and there is something that i don't really understand. To get the Enthalpy of formation for hematite (Fe2O3) at 1200K, I first integrated the constant pressure heat capacity function over the temperature range from...
  4. I

    Gausses Law ^ number 2. I don't get this problem. if the plastic sheets are non-conducting, does that mean the electric field can't penetrate the sheets? and how should i do this problem?
  5. I

    Airplane and Conveyor Belt Debate

    would the plane take off? Can this plane take off given no winds? Theres a quite a bit of discussion on this over at neowin. [Broken]
  6. I

    Simple harmonic motion

    ah yes, i see, it should be v = -A ωsin(ωt + φ), but that's just a typo, i actually had this equation when i wrote it down on paper. But i still don't know how to find phi
  7. I

    Simple harmonic motion I don't get number 1 c, which equation do i use? and in general, how would I be able to find phi? OK, i figured i should find the first derivative of the displacement formula, which becomes v = -Asin(wt + phi) but that still undoable, how...
  8. I

    Difficult problem, PLEASE help. number 3. For part d I'm finding the work by looking at the area under the graph, and a friend of mine used 1.5kdT, which also seems to make sense in this situation, but we're getting 2 different answers. For the change in internal energy...
  9. I

    Quick question 1st law thermodynamics

    What is the equation to find the change in heat of a system that is isothermal? And also, for a PV graph, if the state of the system loops back onto itself, as in it starts at a and ends at a, is the total change in internal energy always 0?
  10. I

    Heat transfer stuff

    well supposedly you're suppose to use some integral crap, but i dun know how to do it.
  11. I

    Heat transfer stuff

    First off, you must be in phys153 in UBC, because I got the exact same problems. For 1, you first find out the energy it took to boil all the water, and that's Lf*m. You then find find the power by dividing the energy you just found by the time. Since H measures the heat transfer for...
  12. I

    Difficult problem, need help

    difficult problem, need URGENT help A small pond has a layer of ice 1cm thick floating on its surface. (a) If the air temperature is −10C, find the rate in cm per hour at which ice is added to the layer. The density of ice is 0.917g/cm3 and its thermal conductivity is 0.592 W/mK. (b) How long...
  13. I

    This problem is MESSED up

    ah yes, it is as i suspected.
  14. I

    This problem is MESSED up

    A 150g copper bowl contains 220g of water. Both bowl and water are at 20 degrees C. A very hot 300g copper cylinder is dropped into the water. This causes the water to boil, with 5g being converted to steam, and the final temperature of the entire system is 100 degrees C. a) how much heat is...
  15. I

    2 thermoexpansion questions

    thermal expansion of: Al = 2.4*10^-5, steel: 1.2*10^-5, brass: 2.0*10^-5 young's modulus of steel = 20*10^10 (NOT 2.0*10^10)
  16. I

    2 thermoexpansion questions

    *bump* no one?
  17. I

    Is the body effected by magnets?

    Once i saw some a show on the discovery channel where they created a strong magnetic field, and they managed to levitage a frog. So I guess humans have that property too.
  18. I

    Class is moving too fast

    ya physics is like that sometimes. What helps me to grasp the points is to do problems, you don't have to do alot, just a little bit of every kind. and just try to scribble down some related stuff on paper while thinking about the concepts. I find that helps alot.
  19. I

    2 thermoexpansion questions

    These are really parts of questions. for number 2, I'm getting 264000kPa, but somehow it just doesn't seem rite, so if you guys can check for me, that'll be great. the other one i don't get is the second part of questions 4 where it...
  20. I

    Gas pressure force

    A cubic metal box with sides of length 20cm contains air at pressure of 1atm and a temperature of 300K. The box is sealed so that the volume is constant and heated to 400K. What is the net force on each side of the box? thanks dudes.
  21. I

    Another thermodynamics

    You see what I don't get is where all the numbers go, and what all the letters in the equation represent. I'm guessing for part A i need to setup 3 equations with 3 variables and R equalling 10.000, 13.946, and 24.174 ohms? and maybe with Tc equalling 0, 100, and 419.414 degrees C respectively?
  22. I

    Another thermodynamics

    another thermodynamics problem For this one its a combination of the wording and the whole resistance that i don't get. In the interval between the freezing point of water and 700 degrees C, a platinum resistance thermometer is used for interpolating the temperatures on the international...
  23. I

    Thermodynamics question i dont get

    I don't get what I'm supposed to do. We haven't even had one lecture on this. Am I to give a definite number value for the temperature? I did this : 0.2898cmK/0.107cm and got 2.7K, am I on the right track?
  24. I

    Thermodynamics question i dont get

    I got this question as part of an assignment. I read the section of the textbook that we were supposed to, and couldn't find anything to help me with, so here goes: To measure temperatures, physicists and astronomers often use the variation of intensity of electromagnetic radiation emitted by...