# Find minimum initial velocity of object

1. Oct 6, 2009

### rajesan

1. The problem statement, all variables and given/known data
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.

2. Relevant equations

v=d/t

3. 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=$$\sqrt{4.9R}$$. Im 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?

2. Oct 6, 2009

### Delphi51

You've got it!