1. The problem statement, all variables and given/known data The muzzle velocity of a gun found at a crime scene is tested by firing the 100 g bullet into a block of mass 9.9 kg. The block is initially at rest on a frictional surface, coefficient of 0.1. The bullet sticks into the block and the combination slides a total distance of 4.5 metres along the surface. Calculate the muzzle velocity of the gun. 2. Relevant equations This collision is inelastic. Fy = 0 = Fn = Fg = mg(Force in y) Ff = uFn = (.1)(9.9kg)(9.8m/s^2) = 9.703N (Friction Force) Fx = ma = (-Ff) + (Fa) vx = dx/t mBvB + mLvL = v'(mB + mL) (B - bullet, L - block) mBvB = v'(mB + mL) (vL = 0) 3. The attempt at a solution I know the frictional force, if I could find a way to figure out the v' in the momentum equation, I could figure everything out. Now I know the displacement, if there was some way I could find the time, or even acceleration. I think I might have ideas on how to taclke the problems, but I can't get too far, I am still going to try, if anyone could help that would very well appreciated. Thank You. I am missing a peice of the puzzle to finish the question. 1. The problem statement, all variables and given/known data Two titanium spheres approach each other head-on with the same speed and collide elastically. After the collision, one of the spheres, whose mass is 300 g, remains at rest. What is the mass of the other sphere? 2. Relevant equations Momentum Conserved m1v1 + m2v2 = m1v1' + m2v2' (v2' = 0, v1 = v2, m1 = .3kg) v(m1+m2) = m2v2' m1v1^2 + m2v^2 = m2v2'^2(should I factor?) v^2(m1 + m2) = m2v2'^2 3. The attempt at a solution Right now I have a feeling that I should be isolating for m2 or something so I can cancel it out when I sub into another equation.