1. The problem statement, all variables and given/known data From the text: "While standing on frictionless ice, you (mass 65.0 kg) toss a 4.50 kg rock with initial speed 12.0 m/s. If the rock is 15.2 m from you when it lands, (a) at what angle did you toss it? (b) How fast are you moving?" mass of me = 65.0 kg mass of rock = 4.50 kg initial velocity = 12.0 m/s initial height = ? initial angle = ? distance = 15.2 m speed of my body (recoil) = ? acceleration of gravity = 9.8 m/s^2 time of flight = ? xo = 0 vo = 0 There is no energy lost to outside forces. 2. Relevant equations These are simply equations i've tried toying with Newton's Second Law F= Ma Projectile Motion Disregarding time v^2 = vo^2 +2a(x-xo) Definition of work Wnet = Integral(F*dx) And these are ones i know i'll need later Conservation of Momentum m1(v1o) + m2(2o) = m1(v1f) + m2(v2f) Conservation of kinetic energy (1/2)m1*(v1o)^2 + (1/2)m2*(v2o)^2 = (1/2)m1*(v1f)^2 + (1/2)m2*(v2f)^2 3. The attempt at a solution I have ideas, but none of them seem to work because i'm not given an angle or an initial height to work with (i'm actually supposed to find the initial angle). I just don't know where to begin on this problem. I know that in order to make that specific distance that initial velocity will need to be at a specific angle, and I have the notion that this is either going to be simple and i'm going to kick myself for overlooking it or it's going to be overly complicated... although the latter is less likely. Please help by giving me a concept to use, steer me in the right direction.