[IB] Physics Extended Essay

1. Aug 27, 2015

Sewager

Sorry I didn't post this using the template :c, since this is not a Physics problem to solve.

Hello everyone, I hope this is the right section to ask this..

I am in a program called International Baccalaureate and I need to write a 4000 word essay on Physics. My investigation is related to 2D badminton projectiles, and my aim is to find an equation to calculate how much velocity is needed for a birdie to travel to the back boundary line of a court, given its position.

I have a hypothesis and I am comparing the it to the real world situation by using video analysis. I am wondering if this lab is sophisticated enough for an extended essay, since it is not a typical investigation on how one variable

Last edited by a moderator: Aug 27, 2015
2. Aug 27, 2015

Staff: Mentor

How are you going to do the calculation? Are you going to use simulations to try to model the flight? Or are you going to try to come up with a complicated formula for the air resistance of the shuttlecock as a function of velocity?

3. Aug 27, 2015

Sewager

Hello! The calculation is just solving kinematic equations for 2d projectile which excludes air resistance. I am comparing this equation with how birdie travels realistically by doing video analysis. Do you think this qualifies as a valid physics lab?

4. Aug 27, 2015

Staff: Mentor

That makes no sense.

5. Aug 28, 2015

Staff: Mentor

Air resistance is so extremely important here that every calculation excluding it is completely pointless.

6. Aug 28, 2015

Sewager

Thank you for your comments. I have added air resistance in my hypothesis now. Do you have any other suggestions?

7. Aug 28, 2015

Staff: Mentor

Then that brings me back to my original questions...

8. Aug 28, 2015

Sewager

The hypothesis, or the calculation is done as a function:

V = f(position, hit angle)

where V is the initial velocity needed for the birdie to travel back so that it lands just at the back boundary line
position is the position of the birdie
hit angle is the angle at which the racket is going to hit the birdie

The real life situation is a video recording of a player hitting the birdie towards the back boundary line. The data of the birdie is extracted using Video Analysis on Logger Pro.

And finally, this report compares the hypothesis with the real life situation in the conclusion.

9. Aug 28, 2015

Staff: Mentor

But my point is that the air resistance effects on a shuttlecock are very complex, including velocity regions with turbulent and laminar flow. Finding or deriving such an equation will be a difficult task, I believe. You might get better accuracy running simulations of the shuttlecock at different velocities, and then using a program to do a discrete simulation of the flight of the shuttlecock.

What experience do you have working with projectile motion subject to air resistance? Like this, for example: https://en.wikipedia.org/wiki/Air_resistance

10. Aug 28, 2015

Sewager

Unfortunately my knowledge of air resistance is very limited. The worst case would be assuming the birdie to be a sphere, and add uncertainties to the function. I believe my teachers would be fine with that.

When you mention simulation, do you mean to create a computer simulation from scratch? Or does such program already exist for grab?

11. Aug 28, 2015

Staff: Mentor

There are simulation programs for fluid dynamics (aerodynamics) that exist. They tend to be pretty expensive, but perhaps your school has access to some of the packages. Check with your Fluid Dynamics department to find out. One such program is COMSOL Multiphysics:

http://www.comsol.com/comsol-multiphysics?gclid=CO65q83pzMcCFcOBfgod9hsLJg

12. Aug 28, 2015

Sewager

Woah! That is very impressive! By the looks of it, this is way beyond my capabilities haha. I will see what I can do, thanks for your help!

13. Aug 28, 2015

Staff: Mentor

One thing you might do is see if you can find some wind tunnel data for shuttlecocks. You may be able to find some curves of drag force versus velocity that others have produced via wind tunnel testing. You can use those curves in your program to calculate the distance the shuttlecock travels. Your program would use time steps of, say, 10 milliseconds apart, and calculate the change in velocity due to height change and due to wind drag. By doing that with enough steps (fine enough granularity), you could get a pretty accurate flight path drawn out.

Best of luck!