Recent content by jybe

  1. jybe

    Sound Interference Problem -- Observer moving between two speakers

    Homework Statement Two identical loudspeakers are driven in phase by the same amplifier at a frequency of 680 Hz. The speakers are 4.6 m apart. An observer stands 9 m away from one of the speakers as shown. The observer then starts moving directly towards the closest speaker. How far does the...
  2. jybe

    Constant pressure heat of reaction -> constant volume q

    It's the change in moles of gas gathered from the equation, used to calculate work done
  3. jybe

    What is the effective spring constant of a charged DNA molecule?

    Homework Statement A molecule of DNA (deoxyribonucleic acid) is 2.10 μm long. The ends of the molecule become singly ionized: negative on one end, positive on the other. The helical molecule acts like a spring and compresses 1.09% upon becoming charged. Determine the effective spring constant...
  4. jybe

    Constant pressure heat of reaction -> constant volume q

    Homework Statement For the reaction below, the constant pressure heat of reaction is qp = −3256 kJ mol−1 at 25 °C. What is the constant volume heat of reaction, qV , at 25 °C? 16 CO(g) + 33 H2(g) ⟶ C16H34(l) + 16 H2O(l) Enter your answer in kJ mol−1, rounded to the nearest kilojoule...
  5. jybe

    Calculating Entropy Change for Gas Sample with Helium and Ideal Gas Equation

    Homework Statement A gas sample containing 3.00 moles of Helium gas undergoes a state change from 30 degrees celsius and 25.0 L to 45 degrees celsius and 15.0 L. What is the entropy change for the gas (ideal gas)? For He, Cp = 20.8 J/k*mol Homework Equations ΔS = Cv*ln(Tf/Ti) + nR*ln(Vf/Vi) =...
  6. jybe

    Thermodynamics: calculating work question

    Thank you so much! Not sure why I was even having trouble with this.
  7. jybe

    Thermodynamics: calculating work question

    It is equal to 1 atm * 19.367 L So to convert 19.367 atm*L to joules, I will multiply by 101.325 J so work is equal to +1962.36 J ? Edit: so to get the change in internal energy I just simply add work to q
  8. jybe

    Thermodynamics: calculating work question

    The original volume of gas is: v= nrt/p v = (0.596 mol)*(0.082058 atmL/(k*mol))*(123 + 173 K) all over 1 atm of pressure v = 19.367 L initially of gas
  9. jybe

    Thermodynamics: calculating work question

    1. Homework Statement What are the values of q, w, ΔU, ΔH for the following constant pressure process for a system containing 0.596 moles of CH3OH ? CH3OH(g, 123.0 ºC, 1.00 atm) ⟶ CH3OH(l, 30.0 ºC, 1.00 atm)Molar heat capacity for CH3OH(g), Cp,m = 44.1 J K−1 mol−1 Molar heat capacity for...
  10. jybe

    How Do You Convert and Round Measurements to SI Units with Significant Figures?

    Oh wow...I actually think that was the problem. I used J this time and got it right but thanks for that heads up
  11. jybe

    How Do You Convert and Round Measurements to SI Units with Significant Figures?

    Homework Statement If I am asked to give my answer in acceptable SI units and to 3 significant figures, how would I express my answer? Homework Equations Answer: 589883.4263 J The Attempt at a Solution My instinct would be to put this in KJ, but I don't know if that's an "acceptable SI...
  12. jybe

    Calculating Safe Distance for Warning: Flower Pot Falling from 21.6m Height

    Homework Statement A flower pot is knocked off a window ledge from a height d = 21.6 m above the sidewalk as shown in the figure below. It falls toward an unsuspecting man of height h = 1.71 m who is standing below. Assume the man below requires 0.300 s to respond to a warning. How close to...
  13. jybe

    How Do You Calculate Work When Compressing Gas?

    Homework Statement What is w when a gas is compressed from 42.1 L to 25.1 L using a constant external pressure of 739 Torr? Remember to include a "+" or "−" sign as appropriate. Homework Equations W = -P(dV) The Attempt at a Solution Pressure = (739 Torr / 760 Torr)*(101.325 kPa) W =...
  14. jybe

    Solve Spring Force Problem: Displacement, Velocity & Acceleration

    Ah, thanks, I finally got the correct answer, but what do you mean I didn't have to find the oscillation frequency? I feel a bit stupid to say this but the equations in my textbook are of the form: a = -Aω^2cos(2pi*f*t)
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