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Homework Help: Physics Extended Essay Topic Question

  1. Mar 2, 2009 #1
    im not sure if this is the right place to ask but..
    im currently taking the International Baccalaureate and i've decided to write my extended essay on physics
    the extended essay is basically a 3000-4000 word essay we write on one of the subjects we learn

    i've decided to write an experimental paper along the lines of:
    "investigation of the effects spinning on a sphere projectile"

    and i've decided to investigate something like how the angular velocity affects the distance it flies or something like that and compare my results to what happens in theory

    are there any other aspects of it i can investiage?
    and is it possible for a high school student to investiage something like this or is it too hard?
    im taking higher level math and physics at the moment
  2. jcsd
  3. Mar 2, 2009 #2


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    Welcome to Physics Forums!

    Do a Google search on "The Effect of Spin on the Flight of a Golf Ball" You will find some interesting information including references to 19th century physicists.

    Also there is an interesting book by Robert K. Adair, "the Physics of Baseball" that discusses curve balls and other types of pitches.

    Do a Google search on "The Physics of Baseball"

    It's a great topic. But realistically, you will probably have to read about what other people have done and write about that. It may be hard for you to actually do experiments unless you have a full array of lab equipment.
  4. Mar 3, 2009 #3
    oh thanks for all the help
    but my essay supervisor said that experimental papers usually get scored higher than theoretical ones
    is it very difficult to set up some kind of apparatus to make this work out?
    and wat kind of lab equipment would i need?
  5. Mar 3, 2009 #4
    Have you considered investigating the spin of snooker/pool balls?
  6. Mar 3, 2009 #5


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    Well, you will need to decide on what kind of ball you want to investigate. My thoughts are: ping pong ball, tennis ball, baseball, or golf ball. You would like to see the effects of spin, so it would be good to have a surface with some irregularities on it. (Dimpling on a golf ball, threads on a baseball). A ping pong ball would be most convenient but they are smooth, so you probably would need to roughen the surface up, perhaps with sandpaper. I would favor the ping ping ball because you can do the work indoors and thus rule out the effect of wind.

    You will need a way to project the ball with a reproducible velocity each time you send it flying. I would suggest a piece of PVC pipe and a plunger that compresses a spring. You can calibrate the spring to get its spring constant. That will allow you to approximate the ball's velocity since the potential energy stored on the spring goes into kinetic energy of the ball plus of course loss due to friction and the kinetic energy of the plunger. You will need a way to make the ball spin while it is coming out of the pipe. Gun barrels have spiral grooves, called rifling, in them which gives the bullet spin. Perhaps you could figure a way to achieve the same effect. (This leads me to suggest you could compare balls without spin and balls with spin and observe the stabilizing effect of spin.)

    It would be nice to have some way to accurately measure the velocity. There are devices called chronographs that gun hobbyists use to measure bullet velocities, but they are prety expensive! I suppose you could use the calculations I suggested above plus an accurate distance and a stopwatch. Or, you could set up a video cam (which you are going to want to do anyhow) and time the flight of the ball past two marked points.

    The easiest way to collect data probably would be to make videos of what happens under different conditions of spin and velocity.

    These thoughts should get you started...
  7. Mar 5, 2009 #6
    @ AEM: thank you for the in depth reply!
    really helped a lot! :D

    @Dadface: yea i've in fact considered it but i thought that something that is airborne will be more interesting. if this is too difficult maybe i'll fall back on that :)
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