The Breakdown

Three points! Is this shot really within the realm of physical possibility?

If we time the flight, we can then apply some ballpark approximations to determine whether the trajectory we see in the video conforms to that flight time. Using our stopwatch we observe that the ball is in the air for 3.8 seconds before passing through the basket. The horizontal distance to the basket from the launch point is approximately 50 meters, and the launch angle θ is about 20 degrees.

Let's use what we know about projectile motion. We know for a projectile that the horizontal motion is independent of the vertical motion, and that in the absence of significant air friction the horizontal velocity is constant. We also know that along the vertical axis, a projectile has a constant downward acceleration due to gravity 9.8 m/s2.

Looking at the horizontal part of the motion and accounting for the launch angle we can then determine the initial speed (v0) of the basketball necessary to cover the horizontal distance in 3.8 seconds. We get

Δx = vhorizontal t = v0cosθt

and therefore v0 = Δx/cosθt = 50 m /[cos 20 (3.8 s)] = 14 m/s

Now if we look at the vertical part of the motion we can determine how far the ball would drop in 3.8 seconds. We'll then compare our theoretical result to the actual vertical distance from the third deck down to the basket that we observe in the video. (We estimate that drop to be similar to the horizontal distance of about 50 meters.) Therefore, based on the time of flight and the initial velocity that we determined above we calculate a vertical drop of

Δy = v0vertical t + ½ at2 = v0 sin t -- ½ gt2 = 14m/s(sin 20)(3.8 s) -- ½ (-9.8m/s2 )(3.8)2 = -53 m

Well, this corresponds pretty well to what we see in the video. Even accounting for the effects of air resistance (which we did not address above to keep things simple) the result isn't altered drastically. The motion recorded in the video (in what appears to be a continuous frame) certainly appears possible according to the laws of physics.

Now whether or not this was done in a single take is another matter!

Adam Weiner is the author of Don't Try This at Home! The Physics of Hollywood Movies.

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5 Comments

I can dig it

I think it's real. Not only because the math works out, but because my eyes don't see anything fishy. What does it for me are the last few frames of the video when you can see a split screen with a second angle. That angle not only matches speed, but wind as well... The other reason I believe it's real is because the wind seemed fairly steady. It wouldn't take a huge amount of tries to figure out the right direction and force with consistent conditions.

it would also take a lot of tries to actually get the ball in the net while vidoe taping.

It's a legitimate shot, it took them several hours, i remember the day they were setting up and there were people talking about it on campus. The ball bounces funny at the end of the video because the "track" around the field is covered in a mushy sponge type surface and absorbs impacts well thus reducing the rebound from the basketball.

i think its possible but what are the chances

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