in the graph above i have made the assumption that the tension of the sling is constant through out the throw, but in fact that won't be the case.

in reality i think it's more difficult to apply big forces at the end (extended arm) of the throw than at the beginning, so the blue force vector (tension of sling) will start big and become smaller while throwing.

the more ellipsoid the throwing motion is:

- the faster your hand needs to be,the more difficult it is to apply force(accelerate)

remember that the slingstone is going to travel faster than your hand most of the time during the throw - the easier it becomes for the arm to withstand the otherwise huge forces caused by small radius of curvature(of a more circular motion)

@JudoP i might be repeating myself here...

the law of physics you used (F=(mv^2) / r) applies to any motion of a body that changes direction (centrifugal acceleration).

You just used the wrong radius.

only in circular motion the radius of the circle equals the radius of curvature, here we don't have circular motion...

you could make make a rough example out of the above graph to understand the difference.

if above is in scale 1:20

then the sling is 80cm(=20*4cm)

let's say the slinger threw 100g stone 50m/s

1)doing it the wrong way and instead of radius of curvature we put the length of the sling 0.8m then F=312.5N

2) the right way would be : radius of curvature=(20*12cm)=2.4m

F=104.1N much less...

this also shows how bad use of long slings loses to good use of short slings

@Mersa the extension (Apex-apoc talks) comes from the combined movement of arm and body but is measured by the initial and last position of the arm

Apex-apoc's model has a multiplication i don't understand and isn't explained

@Apex-apoc feel free to add your drawings and tables in this thread too.