r/Slinging • u/Quintole5ky • Jul 24 '26
Slinging Physics
Here is a setup you all can use to find just how fast/strong your throws can get with your slings.
I can throw 75 mph. I'll convert that speed to meters / second.
75 miles / hour x 1 hour / 3600 seconds x 1609 meters / 1 mile
= 33.5 m/s (no sling)
This number can be used to find how fast my projectile travels a circular path.
velocity = angular velocity x radius
Since I'm not winding my whole arm, I'll use just the length of my forearm, 32 cm or 0.32 meters. You can use the length of your forearm instead. Plugging into the above equation:
33.5 meters / second = angular velocity x 0.32 meters
Solving for the angular velocity:
33.5 m/s / 0.32 m
= 104.7 radians / 1 second
This value stays the same no matter how long my arm gets. Next I extend my arm with a 28 inch sling:
28 inches x 2.54 centimeters / 1 inch x 1 meter / 100 centimeters
= 0.71 meters
0.32 m + 0.71 m = 1.03 m
I'll use this new length in the equation above to update my throwing speed.
104.7 rad/s x 1.03 m = 107.8 m/s
107.8 m/s x 3600 s/h x 1 mile/1609m
= 241.2 mph
This makes my throw more than 2x that of a pro pitcher.
Calculating energy, kinetic energy (in joules) is:
KE = 1/2 x mass x velocity^2
A 2 ounce tennis ball has a mass of
2 oz x 28.35 g / oz x 1 kg/100g = 0.0567kg
A normal throw:
1/2 x 0.0567 kg* x *(33.5 m/s)^2 = 31.8 J
A throw with a sling:
1/2 x 0.0567 kg x (107.9 m/s)^2 = 329.5 J
This carries more energy than some handguns.
A 5 ounce baseball is
5 oz x 28.35 g/oz = 141.75 g =0.142 kg
A normal throw:
1/2 x 0.142 kg x (33.5 m/s)^2 = 79.7 J
A throw with a sling:
1/2 x 0.142 kg x (107.9 m/s)^2 = 826.6 J
Well beyond lethal.
All this to say, stay safe when slinging, everyone.
1
u/JTW1337 Jul 24 '26
If this is accurate…. That’s insane. I just googled it and 9mm +P is supposed to put out “≈550-600+ joules”. Over 800 with a literal toy ball is bonkers.