Question

10. A rollercoaster reaches a top speed of 117 km/hr. Its initial (and tallest)

descent can be modeled by h(t) = 81–4.9t2 , where h is in meters and
t is in seconds. Use this information to solve the following questions:
a How long before the roller coaster reaches the ground?
b) What is the height of the roller coaster just before it begins its decent?
c) Draw a graph to show the decent of the rollercoaster. Include the
coordinate points of the x and y axis.


help!

Answer 1

a) 4.07 s

b) 81 m

Explanation:

a)

h(t) = 0 at full descent.

81 - 4.9t^2 = 0

4.9t^2 = 81

t^2 = 81/4.9

t = 4.07

Answer: 4.07 s

b)

Initial height is at t = 0.

h(0) = 81 - 4.9(0)^2

h(0) = 81

Answer: 81 m