velocity and altitude

Question

A ball is tossed into the air at 40 feet per second from a height of 6 feet. How long will it take the ball to reach the ground? 

The approximate time it took was _ seconds.

Need albegra hw help. thank you!

Answer 1

The equation that represents this situation is

 

h(t) = -16t² + 40t + 6

 

where h(t) is height.

 

 

To find the time the ball reaches the ground, we set h(t) equal to zero.

 

0 = -16t² + 40t + 6

 

0 = -2(8t² - 20t - 3)

 

 

Set the term in parenthesis equal to zero.

 

8t² - 20t - 3 = 0

 

 

Use the quadratic formula to find the value of t:

 

t = (-b ± √(b² - 4ac)) / 2a

 

 

where:
a = 8

b = -20

c = -3

 

Plug in these values into the formula.  You will have two solutions because of the plus/minus sign.  Choose the most reasonable solution.