1. The problem statement, all variables and given/known data A boat is 50.0m from the base of a cliff, fleeing at 5.0m/s. A gun, mounted on the edge of the cliff fires a shell at 40.0m/s and hits the boat when it has fled another 50.0m. a) At what angel above the horizontal must the gun be aimed so that the shell will hit the target? b) How high is the cliff? c) With what velocity does the shell hit the boat? Boat v = 5m/s d = 50m t = 10s Shell vi = 40m/s a = 9.8m/s2 t = 10s 2. Relevant equations All the ones dealing with motion 3. The attempt at a solution a) vix = 100/10 vix = 10m/s SinΘ = o/h SinΘ = 10/40 SinΘ = 0.25 Θ = 14o Therefore the angle about the horizontal must be 14o to hit the boat. b) vyf = vyi+aΔt vyf = 38.7298+(10x9.8) vyf = 38.7298+98 vyf = 136.73m/s Δy = ((136.73+38.7298)/2)x10 Δy = 87.7x10 Δy = 877m Δy = 880m Therefore the cliff is 880m high. c) vf2 = 38.722+(2x9.8x880) vf2 = 1500+17195 vf2 = 18695 vf = 136.73m/s vf = 140m/s x2 = 136.732+100 x2 = 19700 x = 140.357m/s x = 140m/s TanΘ = 140/10 TanΘ = 13.673 Θ = 85.818o Θ = 86o Therefore the shell hit the boat at 140m/s [86o below the horizontal] Are these answers correct? I find the questions when two objects move at the same time very hard to do.