**maximum height is reached at 4 seconds**.

This the vertex of the parabola and is halfway on the trajectory, so **at t=8, h=0, when it reaches the ground**. You can also see this from the original equation h=-16t²+128t=16t(-t+8) when t=8, h=0. Of course, when t=0, h=0 at the start of the trajectory.

- All categories
- Pre-Algebra Answers 12,305
- Algebra 1 Answers 25,233
- Algebra 2 Answers 10,430
- Geometry Answers 5,157
- Trigonometry Answers 2,637
- Calculus Answers 5,997
- Statistics Answers 3,016
- Word Problem Answers 10,085
- Other Math Topics 6,619

81,479 questions

85,659 answers

2,171 comments

69,137 users