Math 161

Sample First Midterm

Problem 6

Dr. Wilson

6. The formula for the height of a ball thrown straight up in the air is

h(t) = -16t2 + 60t + 8

a) We need to find h'(t) and h"(t)

h'(t) = -32t + 60

h"(t) = -32

b) h'(t) = -32t + 60 = 0

when

-32t = - 60

or

t = (-60)/(-32)

= 15/8

c) h(t) = -16t2 + 60t + 8 = 8

when

-16t2 + 60t = 0

Factor

t(-16t + 60) = 0

Set the factors = 0

t = 0

-16t + 60 = 0

-16t = -60

t = (-60)/(-16)

= 15/4