Answer:
a) 39 meters
b) t = 1.8 seconds
Step-by-step explanation:
a)
To find the starting height of the riders, we just need to use the value of t = 0 in the equation of h(t):
h(0) = -9.8*0^2 - 5*0 + 39
h(0) = 39 meters
b)
To find when the height will be equal 0, we just need to use the value of h(t) = 0 and then find the value of t:
0 = -9.8*t^2 - 5*t + 39
Delta = b^2 - 4ac = 25 + 4*39*9.8 = 1553.8
sqrt(Delta) = 39.418
t1 = (5 + 39.418)/(-2*9.8) = -2.2662 s (A negative value for the time is not suitable for the problem)
t2 = (5 - 39.418)/(-2*9.8) = 1.756 s
Rounding to nearest tenth, we have t = 1.8 s
