Physics question...

I

imamartian

if i throw a ball directly up into the air... it will obviously slow down due to gravity, and return to Earth. So i assume at some point at the top of it's journey (parabola?), the ball is actually stationary.
But can we measure, accurately, the length of time it is stationary in the air?
 
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One possible way that I can think of.

Assuming you throw a ball perfectly vertical to a height of 20', it then falls back down perfectly vertical.
The whole process takes, for arguments sake, 10 seconds. You would therefore assume it took 5 seconds to go up and 5 seconds to come down.
But as you say, it must be stationary for a fraction of time.
Therefore, if you were to drop a ball 20' and measure the time taken you may find it only took 4.75 seconds. On this basis you would say it was stationary for 0.5 seconds at the zenith.

(These figures are not accurate and do not reflect the intelligence of the poster. No intention is meant, inferred or implied that this poster is of sound mind and body. ) :LOL:
 
Thanks conny. But not the most accurate answer ;) .

But is the stationary period a uniform length of time? Does the time it's stationary depend on the height the object is thrown? or air pressure? or the strength of gravity?
 
Thanks conny. But not the most accurate answer ;) .

But is the stationary period a uniform length of time? Does the time it's stationary depend on the height the object is thrown? or air pressure? or the strength of gravity?

What do you think I am? :eek:
A flaming scientist? :LOL: :LOL:

Read the disclaimer at the end. :LOL:
 
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I think the concept of stationary is flawed. It's like a switch and it's in either one state or another. That's my guess.
 
I think the concept of stationary is flawed. It's like a switch and it's in either one state or another. That's my guess.
For anything to reverse direction, it has to stop first, this is a fact, quite how the time is measured is another matter.

Wotan
 
Good grief. If I were dextrous and a mathematics teacher (which I'm not), I would advise you that:

1/. The opening post suggests that a ball thrown vertically into the air follows a parabolic route. It in fact follows a straight line - up, then down.

2/. The ball remains at zero velocity for exactly 0 seconds. If this were not the case, then you would be suggesting that it would be floating in thin air for a period of time (not equal to zero) without any force holding it there to counterbalance gravity. With that in mind, joe is correct - it's either moving up or moving down. There is no "resting" time in between these two states.
 
No it doesn't. Not in quantum physics at any rate.


(I was referring to prenticeboy when Lord Landers got in the way.) :LOL: :LOL:
 
So you throw a ball in the air, at a force that is greater or less than gravity, a simple calculation can not be made, in regards of the distance it rises and falls over a period of time.
(I was referring to anyone who cares to read my posts) ;)
 
So you throw a ball in the air, at a force that is greater or less than gravity, a simple calculation can not be made, in regards of the distance it rises and falls over a period of time.
(I was referring to anyone who cares to read my posts) ;)
Talking to yourself again then Lincsy ;)


(only teasing :LOL: )
 
So you throw a ball in the air, at a force that is greater or less than gravity, a simple calculation can not be made, in regards of the distance it rises and falls over a period of time.
(I was referring to anyone who cares to read my posts) ;)
If you throw a ball up with a force less than that of gravity, it won't leave your hand.

As for calculations, there are simple (school child) formulas that work it out.
 
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