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Striders
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Homework Statement
How long will an arrow be in flight if it is shot at an angle of 25 degrees above the horizontal and hits a target 50.0m away at the same elevation?
Known: displacement in x-axis: 50.0m
acceleration in x-axis: 0m/s2
displacement in y-axis: 0m
acceleration in y-axis: -9.81m/s2
theta = 25 degrees
Homework Equations
This question is at the end of a chapter that deals with kinematic equations, so I'm quite certain that one of the kinematic equations must be employed to solve the problem. Those are:
vf = vi + a∆t
∆d = (vf + vi)/2 * ∆t
∆d = vi∆t + 1/2a(∆t)2
∆d = vf∆t - 1/2a(∆t)2
vf2=vi2 + 2a∆d
The Attempt at a Solution
Found the y-component of the displacement vector by doing 50m(tan25) = dy, getting a value of 23.315m. I then used pythagorean theorem to get the length of the diagonal displacement, 55.169m. (this is assuming there is no acceleration due to gravity, which is obviously not the case). That was a dead end so I then basically tried using some of the kinematic equations, just as a guess+ check to see if they'd work. One example attempt is:
∆dy = (viy)∆t + 1/2 * ay(∆t)2
The y-displacement is 0m, so I moved the first term on the right side of the equation over to the left side to get
-(viy)∆t = 1/2 * ay(∆t)2
Divide each side by t to get
-(vi) = 1/2 * a∆t
but I only know one of the three variables and cannot solve. There are a few other, similar attempts to solve the question that ended up not working.
Some help on this problem would be great, I really appreciate everyone taking the time to read and (hopefully!) solve this =)
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