The term "Hang time" is used in athletics to describe the length of time an athlete can jump off the ground. In sports such as long-jump hang time is critical. The longer the hang time the greater the distance that the athlete can jump.

At the point the athlete leaves the ground they have a resultant velocity composed of horizontal and vertical velocities at right angles to each other.

Hang time depends on the vertical or horizontal velocity?

Distance traveled depends on the horizontal or vertical velocity?

Why do athletes seek to increase their horizontal velocity by sprinting down the track before jumping?

Hang time depends on the vertical velocity at take-off. The greater the vertical velocity the higher the athlete can jump and the longer he remains in the air.

The horizontal distance traveled depends on the horizontal velocity and the hang time.
Distance = velocity X time.
Distance can be increased by increasing velocity, time or both. Athletes seek to increase their horizontal velocity with a fast sprint. They also develop powerful jumping styles so that they can increase the hang time.