Answer:v=3.28 m/s
Explanation:
Given
mass of rock 
diameter of circle 
radius 
At highest Point

At highest Point N=0 because mass is just balanced by centripetal Force
thus 




The distance covered by an object accelerating from rest is
D = (1/2) · (acceleration) · (time)² .
In this particular case, 'acceleration' is 9.8 m/s² ... due to gravity.
D = (1/2) · (9.8 m/s²) · (1.67 s)²
D = (4.9 m/s²) · (2.789 s²)
D = 13.67 meters
Each side has to have at least 44 horses
F61160 N. This is further explained below.
<h3>What is the force?</h3>
Generally, We are only interested in the component that operates horizontally since the vertical components all cancel each other out. The pressure difference works on the hemisphere to generate a normal force all over the surface, but we are only concerned with that force's horizontal component. This may be determined by supposing the hemispheres to be two flat circular plates of the same radius as the hemispheres that have been forced together.
Therefore, force is equal to pressure multiplied by area, which is
F= (970 -15 )( * (0.45 m)2)
F=60754 N for each side.
Therefore, each side has to have at least 44 horses
44* 1390 = 61160 N
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It is powered by the Earth's rotation and the moon gives a little boost.
Let t=time to reach the ground=8 secs, g= acceleration of gravity. The speed v on reaching the ground is gt=8g=78.4 m/s where g=9.8 m/s/s approx.