A rock is dropped from a 196-m-high cliff. How long does it take to fall (a) the first 98.0 m and (b) the second 98.0 m?

Answer 1

a. d = Vo*t + 0.5g*t^2 = 98 m.
0 + 4.9t^2 = 98
t^2 = 20
Tf = 4.47 = Fall time.

V = Vo + g*t = 0 + 9.8*4.47 = 43.8 m/s.=
Velocity @ 98 m.

b. d = Vo*t + 0.5g*t^2 = 98 m.
43.8*t + 4.9t^2 = 98
4.9t^2 + 43.8t - 98 = 0
Tf = 1.85 s.