Jlasud:
 
I had to run the calculations by hand, using the drag equation to compute the force of drag, which divided by the mass of the object gives the deceleration.  
 
Fd = .5 x Cd x A x Vsquared  
 
Fd is force of drag
Cd is the drag coefficient. This is fairly constant across the velocities we're talking about for a biconical shape, I conservatively used 0.1. For spherical projectiles, Cd varies between around .15 to .45 at these velocities. I estimated the Cd of spheres using NASA's "Foilsim" program, which is free to use online.
A is the reference area. For some applications the surface area is used, for others cross sectional area. I used cross-section.
Finally, Fd varies by the square of velocity ( as can be seen very clearly in Yurek's graph)
 
I used a projectile mass of 36.8 grams for the calculations.
 
To plot out the flight path you then have to split the motion into its vertical and horizontal components with a little trigonometry (don't forget gravity in the vertical - 9.8m/s) and run the equation for each interval of time you choose. I did the calculation every 1/3 second, one could increase accuracy by decreasing the interval. Anyway, I just applied the deceleration as constant within the interval, which is a source of error, but actually makes the calculated range more conservative. Once you figure the new velocity, you can plot the position at the end of the interval. Then just repeat. It's a little messy and really time consuming, but the next best thing if you, like me, don't know calculus.  
 
In the end, you can just plot the horizontal and vertical positions on a scatterplot to get a visual representation of the theoretical flight path.

Bummer...It doesn't work for me(runtime error)

wow - so now we just need a graphe showing miles per hour instead of metres per second.  
 
And tennis balls decelerate so much because once you factor in the hairs they actually have a massive surface area and corresponsing huge drag effect. Plus they should be spinning a lot faster from a sling than from a tennis racket.  
 
Soooo, can we calculate (I say 'we' I mean you lot ) force of impact for the different projectiles based on weight, area of impact and speed at termination point ?  
 
That would be a very useful chart.

Quote from curious_aardvark on Jun 19^th, 2012, 1:31pm:

 
The force of impact depends not only on the projectile but also on the target. Slinging a stone into a mattress generates lower forces than the same stone hitting a rock cliff, or someone's head.
 
You need to have an idea of either the distance or the time it takes for the projectile to stop, then you can make some estimates.
 
If we can decide on some standard targets eg. supported heavy plank of wood, might be able to make some guestimates.

Soooo, can we calculate (I say 'we' I mean you lot Smiley ) force of impact for the different projectiles based on weight, area of impact and speed at termination point ?  
 
That would be a very useful chart.  
 
...give me till the end of the week and I'll try to get a link to my thesis up. That is precisely what I'm writing part of a chapter on.