Calculating Time and Angle of Impact in Free Fall Physics Problem

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To determine the time it takes for an object to reach the ground and the angle of impact, the equation Δy = Voy * t + (1/2)ay * t² is utilized. The user attempts to solve for time (t) using the quadratic formula, resulting in a calculation involving the values of initial velocity and acceleration due to gravity. There is confusion regarding whether to use the positive or negative root of the equation and how to combine the results to find t. Clarification is sought on the correct approach to solving the problem. The discussion emphasizes the importance of correctly interpreting the quadratic formula in free fall physics problems.
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Homework Statement



http://i1120.photobucket.com/albums/l498/LaLadude/2.jpg

How long does it take to reach the ground? And what is the angle of impact with the ground?

Homework Equations





The Attempt at a Solution


Δy = Voy * t + (1/2)ay * t2
t = (-5 m/s) ± √(5 m/s)2 - 4(1/2)(-9.81 m/s2)(-100m) / 2(1/2)(-9.81 m/s2)

t = -5 m/s ± (4.54)

Is it suppose to be 4.54 or -4.54? And am I suppose to add or subtract the two variables to find t??
 
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Post the entire question.
 
sandy.bridge said:
Post the entire question.

I added a picture link if it'll help.
 
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