|
Question 677191: Can someone check my work please? I hope I'm not missing any steps and that I'm on the right track with this one. Is there a simpler way of doing this? Thank you.
If a stone is tossed from the top of a 270 meter building, the height of the stone as a function of time is given by h(t) = -9.8t2 – 10t + 270, where t is in seconds, and height is in meters. After how many seconds will the stone hit the ground? Round to the nearest hundredth’s place; include units in your answer.
h(t) = -9.8t^2 - 10t + 270
the formula is x = [-b +/- sqrt(b^2 - 4ac)] / 2a
t = [-(-10) +/- sqrt(-10^2 - 4(-9.8)(270)] / 2(-9.8)
t = [ 10 +/- sqrt(100 + 10584) ] / -19.6
t = [10 +/- sqrt(10684)] / -19.6
t = [10 +/- 103.36] / -19.6
t = (10+103.36)/-19.6 = 113.36 / -19.6 = -5.78 cannot be negative seconds 5.78
t = (10-103.36)/-19.6 = -93.36 / -19.6 = 4.76 seconds
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website! You are correct. The only answer is 4.76 seconds. Nice work (and thanks for showing all your steps, which are also 100% correct).
|
|
|
| |
