Question

A cannon mounted on a pirate ship fires a cannonball at 125 m/s horizontally, at a height of 17.5 m above the ocean surface. Ignore air resistance. (a) How much time elapses until it splashes into the water? (b) How far from the ship does it land?

Answer 1

The equation of the motion for the vertical projection of the velocity is:
h= h0 +v0t +at2/2
where v0 = 0;
h0 = 17.5 m, v0 = 0, a = -9.8 m/s2;
a)
0 = 17.5 - 9.8t2/2
t = 1.89 s.
b) the horizontal motion is constant with the velocity of 125 m/s, thus the distance would be
S = Vt = 125*1.89 = 236.23 m/s.