Recent content by TxRationalist

  1. T

    How Long Does It Take for a Flywheel to Reach 125 Rev/Min from Rest?

    you need the equation of motion for rotation. the flywheel is undergoing uniform acceleration; you need to take that into consideration.
  2. T

    Wrong analysis in projectile problem

    I broke the problem down into the x and y components: x = (V0cosθ)t y = (V0sinθ)t - 0.5gt^2 I used the first equation to isolate V0, substituted this into the second equation and solved for t. I then used the first equation again to get my answer for V0. Hope this helps, I have to get...
  3. T

    Wrong analysis in projectile problem

    well, i didn't cancel out the "t" the first time, so that my quadratic equation was in the general form. I corrected that, which led to the form of at^2+c=0. I solved this using my 0.97 m and got a result of 25.7 m/s. Awfully close. I'm going to run it with the same method using your numbers...
  4. T

    Wrong analysis in projectile problem

    I'm not saying I'm right, just that that is what jumped out at me as the path to the solution when I looked at it. I ran the numbers and the quadratic equation gave me a negative for "b squared minus 4ac" also. Unless I did something wrong. I'm going to take another look at it.
  5. T

    Wrong analysis in projectile problem

    you're given an angle of 30 degrees and told that it must not drop more than 3 cm...sounds like 0.97 meters since the question you quoted stated "drop", not rise...but it's your karma...good luck
  6. T

    Wrong analysis in projectile problem

    Shouldn't that Max Height be 1-0.03 meters = 0.97 meters?
  7. T

    Undergrad Facebook: Check Written to Verizon Using Summation Notation

    no, his math is correct. convert e to the i pi to cosine and sine (euler's equation). then take then treat the sum as doing exactly as he says. a sum that goes from 1 to infinity. it converges at a value. this is an oldy but a goodie.
  8. T

    Energy conservation: sled on a hill

    I have to agree with you. seems they left some info out...maybe I'll print this out and look at it at home tonight...good luck
  9. T

    Energy conservation: sled on a hill

    Since they give you the spring constant and the amount of compression, couldn't you figure out what the gain in kinetic energy was from going down the hill? Just a thought, I'm at work and can't spend time on it. Let me know how this works out!
  10. T

    How Do You Calculate the Closest Point of Approach for Two Moving Objects?

    write the equation of motion for each partile, i.e. x0+v1t, etc. and use the distance equation sqrt(x^2 + y^2). then...
  11. T

    What is the Correct Acceleration of a Book on an Inclined Plane with Friction?

    where are you taking the frictional force and V0 into consideration in your equations?
  12. T

    Calculating Building Height Using Balloon Drop Experiment

    seems to me that you have to set up two equations, one for the v0 = 0 at time T and one for v0 = 72.52 m/s at time = (T - 3.7). that's my take...I haven't tried plugging these in, though.
  13. T

    Finding the Equilibrium Price and Quantity for a Simple Linear Equation?

    I came up with the same answer. I didn't major in economics, though...I just assumed (because it sounds right) that you are right, that equilibrium occurs when the supply = demand.