Question

A ball is thrown from the ground toward a cliff of height h with a speed of 30.0 m/s and an angle of 60o
above horizontal. It lands on the cliff 4.00 s later. How high is the cliff?

Answer: 25.5 m

But having difficulty getting this answer

Answer 1

u = 30 cos 60 = 15 m/s
so x = 15 * 4 = 60 meters away if we are interested

now vertical
Vi = 30 sin 60 = 26 m/s
how far up in 4 seconds?
h = Vi t - 4.9 t^2
= 26(4) - 4.9(16)
= 104 - 78.4
= 25.6 I get, wonder if you use 4.9 for 9.81/2