- #1
SammyLP250
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Please help. I think I may be over thinking this problem because it looks very simple.
Determine the minimum initial velocity, v0, and corresponding angle, θ0 needed to kick the ball just over the 3m high fence.
x = 6m
y = 3m
X:
vx=v0x
x = x0+v0xt
v0x = v0cosθ
Y:
vy2=viy2
y = y0+v0yt + .5gt2
vy2 = v0y2+ 2g(s-s0)
v0y = v0sinθ
I first started solving for v0y by setting the vy equal to zero and the y = 3 in the third Y equation.
0 = v0y2 +2(-9.81)(3)
v0y = 7.67 m/s
This is where I get stuck at because when I try to go back and plug in v0 = v0y into the third x equation, I'm still left with two variables, θ and v0. I don't know any other way to approach this formula. I searched online and came across a similar problem that used two different formulas I've never seen before:
y = [(v0)sin2θ]/2g
x = [(v0)sin(2θ)]/g
That person said to divide the first formula by the second and solve for angle first, then initial velocity. When I tried that, my answers where θ = 63.4° and v0y = 8.58 m/s.
The book says the correct answers are θ = 58.3° and v0 = 9.76 m/s
Homework Statement
Determine the minimum initial velocity, v0, and corresponding angle, θ0 needed to kick the ball just over the 3m high fence.
x = 6m
y = 3m
Homework Equations
X:
vx=v0x
x = x0+v0xt
v0x = v0cosθ
Y:
vy2=viy2
y = y0+v0yt + .5gt2
vy2 = v0y2+ 2g(s-s0)
v0y = v0sinθ
The Attempt at a Solution
I first started solving for v0y by setting the vy equal to zero and the y = 3 in the third Y equation.
0 = v0y2 +2(-9.81)(3)
v0y = 7.67 m/s
This is where I get stuck at because when I try to go back and plug in v0 = v0y into the third x equation, I'm still left with two variables, θ and v0. I don't know any other way to approach this formula. I searched online and came across a similar problem that used two different formulas I've never seen before:
y = [(v0)sin2θ]/2g
x = [(v0)sin(2θ)]/g
That person said to divide the first formula by the second and solve for angle first, then initial velocity. When I tried that, my answers where θ = 63.4° and v0y = 8.58 m/s.
The book says the correct answers are θ = 58.3° and v0 = 9.76 m/s
Last edited: