Question 493741
h(t) = -9.8t2 – 10t + 250
set h(t) to zero (ground level) and solve for t:
0 = -9.8t2 – 10t + 250
0 = 9.8t2 + 10t - 250
0 = 4.9t2 + 5t - 125
applying the "quadratic formula" we get:
t = {-5.59, 4.57}
we can throw away the negative solution leaving:
t = 4.57 seconds