math
posted by jen .
A ball is thrown from the edge of a cliff with an initial velocity of 60·m/s upward. Answer the following questions using + (upward) and  (downward) to indicate the direction of the velocity. Ignore air resistance and assume the ball does not hit the ground during the question.
(a) Find the velocity of the ball 5 seconds after it is thrown. 1 m/s.
(b) Find the velocity of the ball 10 seconds after it is thrown. 2 m/s.
(c) How high does it rise above the edge of the cliff (from where it was thrown)? 3 m.

call g = 10m/s^2
v = vi  g t = +60  10t
when t = 5
v = 60 10(5) = 10 m/s
when t = 10
v = 60  10 (10) = 40 m/s
y = yi + vi t  (1/2)g t^2
what is t at the top where v = 0 ??
0 = 60  10 t
t = 6 seconds to top
y = 0 + 60(6) 5 (36)
= 180