Question

A ball is thrown straight up, from 3 m above the ground, with a velocity

Answer 1

Answer:

probably the 2.38 seconds answer

Step-by-step explanation:

start by setting the entire equation equal to 8, since h(t) is the height and 8m is the height we are looking at right now.

$8=-5t^{2}+14t+3$

subtract 8 from both sides to get: $0=-5t^{2}+14t-5$

use the Quadratic equation to find the time, the negative answer does not count.

when you do the quadratic equation you get $\frac{7+2\sqrt{6} }{5},\frac{7-2\sqrt{6} }{5}$

In decimal form that's about  2.38 and 0.42 You'd probably go with the 2.38 seconds because the ball starts at 0 seconds, so the lower number is probably to close to the start point.