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pkc111
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Homework Statement
A projectile fired up into the air from the top of a 75m high cliff hits the ground 500m out from the base.
Calculate the initial launch velocity (U), and launch angle (theta) of the projectile.
Homework Equations
1) v=u+at
2) v2=u2 +2as
3) s=ut+0.5at2
The Attempt at a Solution
Consider up to be positive direction.
Consider vertical component (y component) of motion for entire flight:
a=-9.8 m/s2
s=-75m
uy=Usin(theta)
Sub into Eqn 3:
-75=Usin(theta)t+0.5(-9.8)t2 #EQN A
Consider horizontal component (x component) of motion for entire flight:
a=0
s=500m
ux=ucos(theta)
Sub into Eqn 3:
500=ucos(theta)t #EQN B
Now comes the problem... I have created 2 equations (A,B), but with 3 unknowns (u, theta,t). I think I need another equation ?
This is REALLY bugging me, please help.
Thanks very much.