Question

A ball is kicked 4 feet above the ground with an initial vertical velocity of 51 feet per second. The function h(t)=−16t²+51t+4 represents the height h (in feet) of the ball after t seconds. Using a graph, after how many seconds is the ball 28 feet above the ground? Round your answers to the nearest tenth.

Answer 1

0.6 seconds to 2.6 seconds

Explanation:

From the graph the ball reaches 28 feet after 0.574 seconds

and doesn't fall below that until 2.614 seconds

0.574 rounded is 0.6 seconds

2.614 rounded is 2.6 seconds

Answer 2

0.57 seconds (see graph)

Explanation:

h(t) = -16t² + 51t + 4

h(t) = 28

28 = -16t² + 51t + 4

0 = -16t² + 51t - 24

t1 = 2.613573055

t2 = 0.5739269455 (pick this answer)

The ball will be 28 feet above the ground after 0.57 seconds