# Physics

posted by
**Tammy**
.

A target lies flat on the ground 3m from the side of a building which is 10m tall. A student rolls a ball off the horicontal roof of the building in the direction of the target. Air resistance is negligible. Te horizonal speed with which the ball must leave the roof if it is to srike the target is most nearly

a) 3/10 m/s

b)sqrt(2) m/s

c)3/sqrt(2)

d)3m/s

e)10sqrt(5/3) m/s

time to fall=sqrt( 2height/g)

horizontal velocity= 3/time to fall

You need to put some thinking down. For me to answer is not helpful to you.