Find initial velocity only need hint

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SUMMARY

The discussion centers on calculating the initial velocity of a baseball hit over a bleacher height of 21 meters at a 35-degree angle, with a horizontal distance of 130 meters from home plate. The participant attempts to use the equation vf^2 = vi^2 + 2a(delta x) but encounters a negative value under the square root, indicating an incorrect approach. Key insights include the necessity of treating the problem component-wise and recognizing that the final velocity is not zero upon reaching the bleachers. The solution requires using both horizontal and vertical motion equations to find the initial velocity and time of flight.

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Homework Statement


home run hit and baseball just clears the top of the bleachers.
@= 35 degrees
bleacher height = 21 meters
distance from bleachers to home plate = 130 meters

neglect air resistance

find initial velocity and time of flight

Homework Equations


x comp:
x= vcos@ t + at^2/2
y comp
y= vsin@ t + at^2/2
vf^2= vi^2 + 2a(delta x)


The Attempt at a Solution



The thing is, in order to solve for velocity itd help to know the time and to solve for time itd help to know the velocity. So i thought i'd use vf^2= vi^2 + 2a(delta x) since it doesn't have time in the equation. I got
0= (vi cos 35)^2 + 2(9.8) (130)
i keep getting a negative inside the square root and I am stuck.
I just need a hint into the right direction, am i approaching this problem incorrectly?
 
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Careful now, you wouldn't have an acceleration in the x direction. Also, do you really think the final velocity would be zero? You really need to know what the equations mean and how vectors work. Remember, you have to do it component wise.

So here's what you know: the distance in the y direction the ball travels, and the distance in the x direction that the ball travels. Two equations and two unknowns.
 

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