About physics?

Question

i have an onager (kind of catapult) where the variables are supposed to be changed off and so have different affects of where the projectile travels. the first variable is changing the mass of the projectile, it tells me that increasing the mass decreases time and distance travelling. 2nd variable is sling length when having a too short and too long sling the distance and time is decreased but time is increased for a too short sling. 3rd variable is the throwing arm length it shows the longer the arm the longer time and distance. 4th variable is the skein force shows the bigger the skein force the bigger time and distance travelled. Can anyone explain the results given? I am not sure what the results mean when changing each variable. Can someone give me some info on that? Thanks...(Sorry about the confusing writing:P)

Answer 1

You just need to learn some simple kinematics and dynamics (both part of mechanics). That's usually where any beginning physics book or class starts. You can usually simplify the problems enough that you don't need calculus. For example, if you stretch the spring 5cm and the spring force is 2 Newtons, you can assume the speed is about the same as if the spring applied 1 Newton over the whole 5cm, and you won't be far off. Once you understand F=mA and Hooke's Law for ideal springs, you'll be able to figure out the rest.