Final answer:
The hang time for most athletes is less than 1 second due to gravity. An athlete who jumps higher may have a slightly longer hang time, but it is still typically under a second as per projectile motion equations, which are influenced by Earth's gravity.
Step-by-step explanation:
The hang time (time one's feet are off the ground in a jump) for most athletes is less than 1 second. This is due to the force of gravity which pulls the athlete back down to the ground. The only way for an athlete to stay in the air longer would be to jump higher, which for most athletes can't exceed the gravitational pull significantly enough to achieve a hang time of more than a second.
For instance, an athlete who jumps 0.3 m vertically would have a shorter hang time compared to an athlete who jumps 1.0 m. We can calculate the time using the physics equation for projectile motion, however, for most jumps it will still be under 1 second. This quick hang time is also why quick reactions, such as in catching a dropped object, still result in the object falling a considerable distance even if the reaction time is as fast as 0.5 s.