Refer to the diagram shown.
Assume g = 9.8 m/s² and ignore air resistance
When the rock is launched from a height of 64.7 m,
u = 5.0 m/s, the horizontal velocity
v = 0, the initial vertical velocity
If the rock hits the ground 18.0 m from the base of the cliff, then the time of flight is
t = (18.0 m)/(5.0 m/s) = 3.6 s
The vertical distance traveled is
s = (1/2)*(9.8 m/s²)*(3.6 s)² = 63.504 m
Because this distance is less than 64.7 m, ground level is slightly higher away from the base of the cliff. It is higher by
64.7 - 63.504 = 1.196 m
If the rock is thrown at 10 m/s, the time of flight remains the same because acceleration due to gravity is the same.
Therefore the horizontal distance traveled is
(10.0 m/s)*(3.6 s) = 36.0 m
Answer: The distance will be 36.0 m
