A machine launches a tennis ball at an angle of 25o above the horizontal at a speed of 14 meters per second. The ball returns to level ground. Which combination of changes must produce an increase in time of flight of a second launch?

Increase the launch angle and increases the ball's initial speed.

Explanation:

Given that,

Angle = 25°

Speed = 14 m/s

We need to calculate the changes must produce an increase in time of flight of a second launch

Using formula of time of flight

Where, u = initial speed

g = acceleration due to gravity

t = time of flight

= angle

According to formula of time of flight,

time of flight depends on angle and initial velocity.

So, if the increase in time of flight then the increase the launch angle and increases the ball's initial speed.

Hence, Increase the launch angle and increases the ball's initial speed.