College Physics

Question

Cliff divers at Acapulco jump into the sea from a cliff 36 m high. At the level of the
sea, a rock sticks out a horizontal distance of
10.4 m.
The acceleration of gravity is 9.8 m/s
2
.
With what minimum horizontal velocity
must the cliff divers leave the top of the cliff if
they are to miss the rock?
Answer in units of m/s.

Answer 1

Assuming there is no initial vertical velocity, calculate the time it takes to reach the water, then divide the horizontal distance by that time to get the minimum required horizontal speed.

 

h = gt²/2 ⇒

 

t = √(2h/g)

 

Plug in 

 

h = 36 m

g = 9.8 m/s²

 

and get t in seconds,  Then the minimum required horizontal speed is 

 

v = d/t

 

Plug in 

 

d = 10.4 m

 

and the result for t above, and get v in m/s.