Recent content by SilverVenom

Imagine a ball launcher which is composed of two rubber wheels that spin in opposite directions such that a ball that is fed in, will be launched from the other side at X m/s. I am trying to figure out how many RPM the wheels need to be spinning to launch a ball at Velocity X. Knowns: The...

Sorry I took so long to get back to you. I've had internet outages for the past week or so. :( I worked over your equations, however I am still a little bit confused. In your first equation m ds/dt - D*s = -mg, where D is drag coefficient (6*pi*R*viscosity), if you could walk me through what...

Hey, I have a question about how to calculate the air resistance, and eventually how much more energy is required to get the same result, once air resistance has been factored in. I have thought of two ways to solve the problem: One way requires multi-variable calculus, which I havn't had...

I just finished checking it through with the original formula you posted, and I get the same answer if I plug in either the ideal angle, or plug in the min velocity and solve for the angle from the original. These latest two formulas work wonders for their small size. :smile: The hardest part...

Thanks for adding those extra formulas to find the most efficient path, just to clarify: Continuing with my previous example, if a = 20, b = 10, then: My ideal angle would be 58.3 degrees? Which would require a minimum velocity of 17.8m/s? Thanks so much for your help!

Ahh, now I am beginning to understand this reasoning a bit more. So if a choose an angle that "looks" appropriate, and the tangent of that angle is greater than b/a, then it should have a valid solution? Thanks for the quick replies!

Because the denominator turns to zero, I assume? So then, how do I find my initial angle? My only thought would be to use another formula to find the apex of the flight...

The arc tangent of b/a

My initial angle is from atan(b/a), is this correct? Also, am I reading the denominator of your equation correctly? "(2*cos^2)*((a*tan)-b)"

Sorry for the double post, but, something about this is not working out correctly. When I do my work, assuming: g = 9.81, a = 20, b = 10 I get 73.533m/s for the initial velocity, which is close to 165mph! Now, for a quick reality check, I know for a fact that I don't have to chuck a tennis...

HallsofIvy: I think tennis balls are supposed to have a mass of 57 grams, close to .1kg just for mathematical simplicity, at least while I try to understand the math. :smile: Thanks a lot for the help! I knew there was a "simple" way to figure this problem out. Special thanks to Arildno for...

Sorry I didn't mention that earlier. Here is a really simple diagram to help illustrate the scenario: http://img515.imageshack.us/img515/2257/ballsb9.jpg Simple, but I hope it helps convey the idea. Thanks for the help so far! - Peter

The ball is a standard tennis ball. Air resistance does need to be taken into consideration. http://wings.avkids.com/Tennis/Book/ball-01.html" The specs from that website should be appropriate. Thanks for the quick reply, - Peter

Hello, I hope I posted this question under the right forum. :blushing: I am working through a problem I thought of a few days ago, just for fun, and it's driving me insane. I've gone through numerous textbooks, none of which seem to have just the right equations. Here is the scenario: I...