# Projectile Motion Help?

passmorea
A ball is fired out of a cannon and flies a total distance of 235 meters. The ball has a total flight time of 47s. What is the maximum height and the vertical and horizontal components?

df= 235m
t= 47s

## Homework Equations

d=vt
df=di+vit+(1/2)at^2
vf=vi+at
vf^2=vi^2+2a(df-di)

## The Attempt at a Solution

d=vt
235=47v
v=5 (i dont know where to plug this number into. I could answer this problem if it gave me the trajectory angle, but it is unknown?)

victorlee2
d=vt
235=47v
v=5

ok so u basically have the horizontal component here. if u put subscripts, it is dx = vx*ttot
therefor vx = 5m/s

ok next, you know at in projectile motion, at max height velocity = 0m/s right?
so vf = vi + at. t = 1/2 the total time because tup = tdown for projectile motion of the same height. remember this is all in the y component, so a would = 9.8m/s^2. plug and solve for vi ( which is also vy ) and u have ur y component.

next for maximum height you have found you vy component so what do u do? find another formula! what do we know again?? v at max height = 0m/s right? and you have vi sooooo which formula includes vf <--- v at max and vi AND DISTANCE IN THE Y DIRECTION??? you already know. plug and chug and u shuld have it.

passmorea
ok, so the horizontal component is 5. I didn't know where the 5 went.