Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Five-bladed Fan

  1. Jan 1, 2010 #1

    Char. Limit

    User Avatar
    Gold Member

    Here's a question that I thought up while shooting darts through a five-bladed ceiling fan. I'm lazy, so I'll use symbols for the constants in the equation.

    Say I have a five-bladed fan of radius R, with a blade width W, spinning at angular velocity V. I shoot a dart of length L through the fan at a speed S. What is the probability that I hit the fan?

    Just do the equation, I'll fill in the measured constants later.
  2. jcsd
  3. Jan 2, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi Char. Limit! :smile:

    Calculate how long it takes the dart to pass through the fan, and how far round the fan goes in that time. Then subtract that distance from the distance between the blades. :wink:
  4. Jan 12, 2010 #3
    Awesome problem. But there's something missing here. It looks like the blades are rectangular. So...we either need to specify some definite radius at which you throw the dart, or define precisely the probability distribution determining where in the circle you are likely to throw the dart.

    Let's see what you come up with, mr./mrs. char!
  5. Jan 12, 2010 #4

    Char. Limit

    User Avatar
    Gold Member

    The blades are about two feet long, and the radius of fire is about 1.5 feet.

    And it's Mr. for future reference (learn something new every day.)
  6. Jan 19, 2010 #5

    Char. Limit

    User Avatar
    Gold Member

    Ok, thanks. Just two questions: what do the omega and the little v represent? I've measured the other three (W=5.25 in, R=24 in, and L=3 in). Now I just need those two.
  7. Jan 19, 2010 #6


    User Avatar
    Gold Member

    Man checks into hospital with dart buried up to hilt in forehead. Sez victim: "Who knew a ricochet could pack so much energy?" News at 11.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook