posted by cole .
A man tosses a penny up into the air above a 100 ft well with a velocity of 5 ft/sec. The penny leaves his hand at a height of 4 ft. How long will it take for the penny to reach the bottom of the well?
height of penny = -16t^2 + 5t + 4
to reach bottom of well, h = -100
-16t^2 + 5t + 4 = -100
16^2 - 5t -104 = 0
using the formula:
t = appr 2.7 or a negative, which we'll reject