- #1
FredericChopin
- 101
- 0
Homework Statement
http://imgur.com/BPPbwpu
Homework Equations
s = ((v + u)*t)/2 - an equation of motion for constant acceleration, which is applicable in this situation.
The Attempt at a Solution
Let u be the velocity at which the projectile was launched.
It is given that sx = symax. So:
sx = symax = u*cos(θ)*t
Thus:
symax/t = u*cos(θ)
Now, in the y-direction, the projectile was given initial velocity u*sin(θ), and at the top of its trajectory (where it has maximum height symax), it has final velocity 0 m/s. Thus:
symax = ((0 + u*sin(θ))*t)/2
, which means:
symax/t = u*sin(θ)/2
However, since symax/t = u*cos(θ) :
u*cos(θ) = u*sin(θ)/2
Thus:
cos(θ) = sin(θ)/2
2*cos(θ) = sin(θ)
2 = sin(θ)/cos(θ)
2 = tan(θ)
θ = tan-1(2) = 63.4349°
However, this was marked wrong.
Can somebody see what could have gone wrong?
Thank you.