A person standing at the edge of a seaside cliff kicks a stone over the edge with a speed of vi = 14 m/s. The cliff is h = 39 m above the water's surface.

Question

(a) How long does it take for the stone to fall to the water?

(b) With what speed does it strike the water?

Answer 1

(a)
d = Vi*t + (1/2)*a*t^2

Keep in mind that to use the equation to find time with respect to displacement in height, consider only the vertical component of the initial velocity. (You did not specify a direction for the initial velocity).

(b)
Having found the time from part (a), use a = (Vf - Vi)/t to find the velocity when it hits the water.

Answer 2

a)2.910
b)11.089