# What is hang time?

by ThetaPi
Tags: time
 P: 9 Could someone kindly explain to me what hang time is, in the context of 2D projectile motion? Enlighten me on the equations of motion that might be applicable to such a problem. In other words, given a projectile launched at $$\theta$$ above the horizontal with an initial velocity of $$v_0$$, how do we calculate the hang time? Thoughts. We need to calculate the time it takes for the projectile to reach the maximum height of the trajectory ($$t_1$$), and the time it takes to hit the ground after attaining its maximum height ($$t_2$$), and then add up $$t_1+t_2$$. I think that it will be convenient to use the y-component of $$v_0$$. The maximum height of the trajectory is $$|1/2gt_2^2|$$. We can use this in the equation $$s_y=v_{0y}t_1-1/2gt_1^2$$ to find $$t_1$$. I am rather confused...some posts I saw while browsing the forums said that the initial velocity does not affect the "hang time". Thank you TS
 P: 1,084 velocity in the x-direction doesn't have an affect on hang time. hang time to me is simply the time that the projectile is in the air.
 P: 9 I know that, but how do we calculate that numerically? I presume that hang time is dependent on the y-component of the initial velocity? Thanks again.
P: 1,084

## What is hang time?

right. you've written the equation that is going to give you the answer. If it is a projectile starting and stopping at the same y value, you know that maximum height has to be at half the total time its in the air. try working through it you seem to understand the concept

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