The quarterback throws a football at 25 m/s at a certain angle above the horizontal. If it took the ball 2.5 s to reach the top of its path, how long was it in the air?

The ball was in the air for 5.0 seconds

Explanation:

When the ball is thrown above at a certain angle from the horizontal it follows a projectile motion.

The ball has a specific vertical and horizontal velocity.

The time take for the ball to reach at the top of its path is also the time taken by the vertical velocity vector to become zero. This is the first half of the projectile motion (ball is going up).

For the second half, the ball comes down and it accelerates with same gravitational acceleration from which it was decelerating in the first half. Hence the time to come down will be the same 2.5 seconds.

So the total time the ball was in the air is twice of 2.5, i. e,

5.0 seconds