SOLUTION: I have this problem: A roof shingle is dropped from a rooftop that is 100 feet above the ground. The height y (in feet) of the dropped roof shingle is given by the function y=

Question 745041: I have this problem:
A roof shingle is dropped from a rooftop that is 100 feet above the ground. The height y (in feet) of the dropped roof shingle is given by the function y=-16t^2+100 where t is the time (in second)s since the shingle is dropped. Graph the function.
I have worked out that if I solve for t, t=2.5. But how do I proceed in graphing? My teacher doesn't explain anything and this problem is on my review sheet. We didn't ever see word problems like this in the chapter. Any help you can give me would be very much appreciated.
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
y=-16t^2+100
since co-efficient of x^2 is negative the parabola opens downwards
find the two values of x for which y=0
t= +2.5 and -2.5
the two points are (-2.5,0) and (2.5,0)
when t=0, y=100 you get another point (0,100) this is the vertex of the parabola.
take t=+/-1, y1=84 (+/-1,84)
take t=+/-2,y2=68(+/-2,36)
The parabola is symmetric about the axis of symmetry.
Plot the points and trace a symmetric curve.

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