# Projectile Motion: A boy throw a ball above a barn roof

## Homework Statement

A boy attempts to throw a ball over the roof of a barn 11m high with an initial velocity of vsub0=12m/s. Determine the angle theta, at which the ball must be thrown so that it reaches its maximum height, which is at the roof of the barn. also find x where the boy must stand to make a throw, if the ball is thrown 1m from the ground.

## Homework Equations

x=vsub0*costheta*time
y=Vsub0sinetheta*time-1/2 gt^2

or if max height is given 11m maybe, h=vsub0^2sin^2theta / 2g

## The Attempt at a Solution

if i use equation for max height I cant get the angle but im thinking of combining the vertical and horizontal comp of displacement if I could get some hints to solving the angle or maybe the total x distance, but im stuck with a time missing then made me confused....

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vela
Staff Emeritus
Homework Helper
Why can't you find the angle using the max-height formula? It should work.

syntax error for me...i cant get the angle

vela
Staff Emeritus
Homework Helper
Why? Show your work so we can see where you're getting stuck.

i get errors here
11=12^2sin^2theta / 2*9.8
11*2*9.8=144sin^2theta
√215.6/144=√sin^2theta
theta=arcsin(1.22) then error

vela
Staff Emeritus