Question

During a practice match, a softball pitcher throws a ball whose height at any instant from ground level is given by the equation h = $-16t^2$ + 24t + 1 , where h = height in feet and t = time in seconds. How long does it take for the ball to reach a height of 6 feet from the ground level?

• A. 2.2 secs, 3.8 secs
• B. 5.4 secs,6.2 secs
• C. 0.25 secs,1.25 secs
• D. 7 secs, 5 secs

Answer 1

The correct option is C

0.25 secs,1.25 secs

Given, height = 6 = -16$t^2$ + 24t + 1

$\Rightarrow$16$t^2$ + 24t + 5 = 0

$\Rightarrow$ (4t-1) (4t-5) = 0

t = $\frac{1}{4}$,$\frac{5}{4}$ or 0.25,1.25

It takes 0.25 secs and 1.25secs for the ball to go up and down respectively.