Question

A ball is thrown from an initial height of 4 feet with an initial upward velocity of 23 f/s. The ball's height h (in feet) after t seconds is given by the following. Find all values of t for which the ball's height is 12 feet.

Answer 1

Time taken = 0.85 and 0.59 (Approx.)

Explanation:

Given:

Initial height = 4 feet

Initial upward velocity = 23 f/s

Equation;

h = 4 + 23t - 16t² for h = 12 feet

Find:

Time taken

Computation:

h = 4 + 23t - 16t² for h = 12 feet

12 = 4 + 23t - 16t²

16t² -23t + 8 = 0

t = [-b±√b²-4ac] / 2a

t = [23±√23²-(4)(16)(8)] / 2(16)

t = [23±√529-512] / 32

t = [23±4.12]/32

Time taken = 0.85 and 0.59 (Approx.)