Question #1227

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?

Expert's answer

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.

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.

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