Find minimum initial velocity of object

[rajesan]

Homework Statement

Find the minimum initial velocity needed for a ball starting from the middle-top (highest point) of a semicircular mound with radius R to go over without touching the mound if the initial velocity has only a horizontal component.

Homework Equations

v=d/t

The Attempt at a Solution

this was a question on a test i just had. i didn't have time to prepare to well for this test so i have no idea how i did. i just used the formula v=d/t and substituted the variable R (radius) for d. then i solved fort which equaled t=R/v. then i plugged this value of t into the formula
"$$\Delta$$d=vt+.5at$$^{2}$$. with this i just solved for v and i got v=$$\sqrt{4.9R}$$. I am pretty sure it is wrong and that i was supposed to use some formula for circular motion or something. could you please help me figure this question out?

 

[Delphi51]

You've got it!