# B Time of flight objects in air versus in vacuum

Tags:
1. Oct 30, 2016

Hello
I needed to know a logical answer to the question that whether the time of flight of the objects in air increases or decreases as compared to vacuum? Why?

2. Oct 30, 2016

### Staff: Mentor

What do you think?

3. Oct 30, 2016

I reckon that the time should decrease as the height approached (of a vertically thrown object for instance) decreases

4. Oct 30, 2016

### Staff: Mentor

What do you mean by "the height approached"?

5. Oct 30, 2016

Max vertical height approached

6. Oct 30, 2016

### Staff: Mentor

Time of flight certainly decreases as the max height thrown decreases, but your original question was about an object thrown in the atmosphere vs in space.

7. Oct 30, 2016

Oh yes! If we consider two similar heights in the journey of an object in space and atmosphere. The one in the atmosphere will take more time, I guess, since it has to sail through air drag. Right?

8. Oct 30, 2016

### Staff: Mentor

That's right. Air's a real drag, ain't it?!

9. Oct 30, 2016

Yes

10. Oct 30, 2016

### jbriggs444

Details matter. Is the object at rest, falling or rising? Does it have a spin? What about its horizontal velocity? What about its shape?

11. Oct 30, 2016

### Staff: Mentor

Am I missing something here? I see no description at all about what kind of objects we're discussing and what is making them move. It matters a lot if we're talking about a bowling ball or a glider, for example.

12. Oct 30, 2016

### Staff: Mentor

Unless the question is about throwing something with a rocket engine, I don't see how any of that matters since we're talking about vacuum vs non vacuum. Seems pretty clear cut to me.

13. Oct 30, 2016

### jbriggs444

Take, for instance, the case of a piece of [indestructible] paper hurled upward at escape velocity. It takes longer to hit ground in vacuum than in air.

14. Oct 30, 2016

### Staff: Mentor

If you drive a golf ball or throw a paper airplane in a vacuum it will come down faster than if you do it in air.... unless it has topspin or is flying upside-down in which case it may generate negative lift and fall much faster than when either creating positive lift or thrown in a vacuum.

Last edited: Oct 30, 2016
15. Oct 30, 2016

### Staff: Mentor

I see. My mistake then. I hope I haven't led the OP astray.