Solving Physics for Human Slingshot Model in Excel

[Guaps]

I want to build a fun, but potentially dangerous toy - a human slingshot (into a lake). I'm trying to figure out the physics of a contraption like this but it's been 20 years since I took a physics class. The formulas I'm finding online are giving me some unrealistic numbers, so I know I'm doing something wrong. I want to make a model in Excel that I can enter the variables and figure out what is reasonable. So I need the formula/formulas so I can set up the model.

I want to know the formula that if I enter 3 of 4 variables (launch speed, range, angle of launch, and maximum height) I can solve for the fourth. For example, I want to throw someone 100 feet, at a max height of 30 feet at a 30 degree launch angle. What speed would they have to leave the sling shot at? Or I want to launch 100 feet and I can launch them at 40 mph, at about 30 degrees. What is their max height? etc etc etc.

This way I can figure out if the speed/height are within a safe limit. Or if I need to shorten the distance. Or if I can launch farther, etc.

Thanks! You can come try it out if I survive the first launch. haha

 

[berkeman]

Thread closed for Moderation...

EDIT -- thread will stay closed. We do not discuss dangerous activities here on the PF.

EDIT (DaleSpam) - similar devices have led to permanent paralysis and death. The only recommendation from PF on constructing such a device is to NOT do it. All responses to the OP have correspondingly been deleted.