Recent content by robertjordan

  1. R

    I Partitioning a whole number in a particular way

    Another example is: w1 = 11 w2 = 39 w3 = 3 W = 53 P = 25 ROUND(P*w1/W) = 5 ROUND(P*w2/W) = 18 ROUND(P*w3/W) = 1 This sums to 24 but we have 25 pieces.
  2. R

    I Partitioning a whole number in a particular way

    I'm not sure what round off means. If round off means raise anything with a decimal >= .5 the next whole number and anything with a decimal <.5 to the next whole number down, then the example will still lead to 18 pieces being assigned.
  3. R

    I Partitioning a whole number in a particular way

    Thanks for the replies. I don't mind so much favoring someone more than others as long as: (ai<=wi) is not violated we assign exactly P pieces of pizza. no more, no less only whole slices can be assigned (no fractions for ai) For example, if we have w1 = 25 w2 = 9 W = 34 P = 17 Then...
  4. R

    I Partitioning a whole number in a particular way

    Hi, Let W be the sum of all the people's weights, let P be the total number of pizza slices available. If: I have P slices of pizza (P<=W) I have n people I want to split the pizza with I want to use people's weight to determine how many slices they get (more weight -> more slices) I don't...
  5. R

    I What are the physics behind a bell siphon in an aquaponics system?

    In the past I've made these bell siphons following these instructions: http://www.affnanaquaponics.com/2010/02/affnans-valve-detailed-explanations-of_9459.htmlI've had good success but that was just blindly following instructions and now I am just very interested in knowing the effects of...
  6. R

    I What are the physics behind a bell siphon in an aquaponics system?

    It's definitely growing in popularity! I think it's fun because you get to combine 3 hobbies: raising fish, growing plants, and building hydraulic systems (siphons, pumps, waterfalls, filtration, etc.) Apparently the physics of a bell siphon are pretty complicated, but do you think you can help...
  7. R

    I What are the physics behind a bell siphon in an aquaponics system?

    I'm trying to build a home aquaponics system, and a key component of the design I got off the internet is a bell siphon. So I'm trying to understand the physics of this siphon effect so I can optimize the weight and dimensions of the siphon to fit the size of my system.From what I read on the...
  8. R

    Measuring torque acting on motor shaft?

    I have an electric motor that I am using to turn an auger to dispense pet food. I want to measure the average torque required to turn this auger at a given rpm. I know Powerin = Voltage into motor * Current into motor and Powerout = Torque exerted by shaft * RPM of auger and Powerout...
  9. R

    Can Piezoelectric Crystals in Shoes Charge Your iPod?

    It takes 120 J of energy to light two 60-watt light bulbs for 1 second, right? And the average phone takes 18000 Joules of energy to completely charge so that's only 150 steps!... I'm sure there is something wrong with that line of thought, haha
  10. R

    Can Piezoelectric Crystals in Shoes Charge Your iPod?

    I was inspired by this article http://science.howstuffworks.com/environmental/green-science/house-music-energy-crisis1.htm to wonder if one could put piezoelectric crystals in the sole of a shoe and perhaps harness the energy to charge their iPod?Can someone let me know if this is feasible and...
  11. R

    Calculate attractive force between Cu2+ and O2- ions.

    The equation F= ke(|q1q2|)/r2 looks good. So if I plug in 3.204 × 10^-19 coulombs for q1 and -3.204 × 10^-19 coulombs for q2 (because O2- has a net charge equal to -2 times the charge of an electron and Cu2+ has a net charge equal to twice the charge of an electron), then I get 2.307*10-8...
  12. R

    Calculate attractive force between Cu2+ and O2- ions.

    Well I don't know the force equation, my teacher only gave us the equation for bonding energy... Perhaps since energy=force*distance we can find force by dividing our energy equation by some distance? I'm still stuck but I see now that z_1= 2 and z_2=-2. Any more help?
  13. R

    Calculate attractive force between Cu2+ and O2- ions.

    Homework Statement Calculate the attractive force between a pair of Cu2+ and O2- ions in the ceramic CuO that has an interatomic separation of 200pm. Homework Equations E_A= -\frac{(z_1\cdot e)(z_2\cdot e)}{4\pi\cdot\epsilon_o\cdot r} Where z_1 and z_2 are the valences of the two ion...
Back
Top