If a projectile is fired straight up at a speed of 10 m/s, the total time to return to its starting position is about ?

When I use the quadratic formula, I get -8.97

1 answer

How can the time be negative?

0=10t-4.9
0=t(10-4.9t)
t=0, t=10/4.9 sec are the solutions

In the quadratic equation:
(-10+-sqrt100)/-9.8 = same answers.