How do objects manage to move?

[Jugs Monthly]

When a stationery object is struck by a moving object, such as a golf ball hit by a golf club, does the stationery object instantly move when struck. Or does it have to accelerate from 0 mph to say, 32 mph. If so, there must have been a moment when it reached 16 mph, and before that 8 mph and 4 mph and so on. As you cannot keeping halving your speed forever, or can you, the question is (1) at what point does it stop being stationery and become moving and (2) what speed does it start off at?

As I have no training in physics I can only come up with two possible answers, (1) 0 mph is somehow a speed with the same characteristics as any other speed, or (2) this sounds really weird but here goes, time does not flow but pulses. One pulse the object is stationery, and in the next pulse it is moving, meaning nothing exists between pulses in a time sense.

Looking at it another way, if an object has to accelerate from 0 mph how can it ever start to move at all, if at any moment no matter how slow it's moving, it was moving at half that speed previously? I guess the same aplies in reverse to any object coming to a rest as well.

Help, it's all too much.

[Sayonara]

If Blike ever gets around to fixing or removing the Latex module on the forums, check out this thread:

http://www.scienceforums.net/forums/showthread.php?t=3547

[Tesseract]

This reminds me of a paradox, one of the infinity paradoxes.

[alt_f13]

I don't see why accelleration can't be on a macroscopic scale. After all, an ants point of view is just as valid as an elephants. I'm sure you would see the accelleration in super slow motion on a tiny tiny scale.

 

But there is some ammount of compression in a golf ball when it is hit anyway. It is squished into an ovoid shape, so the leading face of the ball actually does accellerate from zero to its final speed in a measurable ammount of time.

[BPHgravity]

Zeno Dichotomy Paradox

[Tesseract]

Zeno Dichotomy Paradox

Thank you, Im going to look that up.

 

Here it is seems similar:

"Dichotomy paradox: Before a moving object can travel a certain distance, it must travel half that distance. Before it can travel half the distance it must travel 1/4 the distance, etc. This sequence goes on forever. Therefore, it seems that the original distance cannot be traveled, and motion is impossible."

From: http://www.jimloy.com/physics/zeno.htm

[alt_f13]

There is a minimum unit of space.

[John]

http://www.shu.edu/html/teaching/math/reals/history/zeno.html

 

Jugs, the reason "it's all too much" is that it contradicts our senses, but it also makes reasonable sense. That's never an easy thing for our brains to work out.

 

Zeno came from a school of thought that claimed all motion was simply a series of illusions, shifting perceptions and opinions. In reality, according to this philosophy, all of the universe was fixed, never changing. According to the site I linked above, modern mathematics has enabled us to "solve" Zeno's problems to some satisfaction, but there is still some debate.

 

The problem with this, as with any philosophy this broad in implication, is that our mathematical system is based on how its various contributors over the centuries have perceived the universe, both concretely and abstractly. However, this belief in an unchanging universe claims that all our perceptions are false. If that's the case, then how can a system we came up with to describe our perceptions ever hope to prove or disprove the theory?

 

If you're going to be an ancient philosopher, be an atomist. At least they proved definitely right in the end.

[Jugs Monthly]

Thanks for the replies, esp John for that cool link. Although I understand what Alt f13 says about objects deforming, I'm non the wiser concerning if some parts or areas of a struck object moves instantly or accelerate from rest.

Thinking about it though, the striking object would have to come to a standstill for a moment to allow a non deforming object to accelerate from 0mph

[alt_f13]

Thinking about it though' date=' the striking object would have to come to a standstill for a moment to allow a non deforming object to accelerate from 0mph[/quote']

 

Not if the non-deforming object instantly changed speed. And just because an object seems solid, it doesn't mean molecules aren't moving from their supposed place on the object, temporarily slowing down before being pushed through with the rest of the object.

 

I'm sure there is tonnes of compression at a molecular level between a golf ball and club.

[Tesseract]

This also reminds me of Zenos arrow paradox that states how do we see motion if the frozen picture of a moving arrow is the same as a stationary arrow?Wich I dont think is a paradox anyway.

[alt_f13]

The arrow paradox

Finally, in the arrow paradox, we imagine an arrow in flight. At every moment in time, the arrow is located at a specific position. If the moment is just a single instant, then the arrow does not have time to move and is at rest during that instant. Now, during the following instances, it then must also be at rest for the same reason. The arrow is always at rest and cannot move: motion is impossible.

 

This paradox is resolved by calculus as follows: in the limit, as the length of a moment approaches zero, the instantaneous rate of change or velocity (which is the quotient of distance over length of the moment) does not have to approach zero. This nonzero limit is the velocity of the arrow at the instant.

 

http://www.nationmaster.com/encyclopedia/Zenos-paradoxes

 

[edit] <--- teehee.

If zero time passes, then zero movement happens as movement is distance/time... so that is a silly paradox.

[Tesseract]

http://www.nationmaster.com/encyclopedia/Zenos-paradoxes

 

 

Cool.

 

Exactly I said it wasnt a paradox...