Galileo's experiment

[cyruseternity]

Plz guys help me....in a book it is stated that according to galileo's experiment of free falling objects, change in velocity with distance is not constant, it decreases with the increasing distance of fall.... What does it mean..??

[Strange]

I assume it is referring to air resistance.

 

Here is a practical demonstration: http://blogs.scienceforums.net/swansont/archives/15447

[cyruseternity]

Ya....but how can d velocity decrease with increase in distance of fall.?

[imatfaal]

Taja - try and be a bit more precise with your questions. You are asking members to help out - so the least you can do is write accurate and consistent questions

 

 

 

... change in velocity with distance is not constant, ...

 

...velocity decrease ...

 

So is it velocity or change in velocity (which we call acceleration) which decreases with the length of time the object has been falling?

 

Strange has provided a link for "change in velocity" diminishing - and frankly I cannot think of an everyday circumstance in which velocity will decrease during a fall

[cyruseternity]

Sry.....it is actually the change in velocity....

[imatfaal]

So I presume that Strange's link made the point clear. Air resistance is what you want to look at. You could also try googling "terminal velocity"

[cyruseternity]

Ya it wrkd...thanks both..

[swansont]

No, it's not air resistance. The question is asking just what it says.

 

What is being described is that dv/dx gets smaller. As the object falls, its speed increases linearly with time, since v = at for constant a. Let's approximate the acceleration as 10 m/s^2. After 1 second the object is moving at 10 m/s and has dropped 5 meters. The change is speed per length is 2 m/s per meter. After 2 seconds the speed has increased another 10 m/s and it has dropped an additional 15 meters, so the change in speed per length is 0.67 m/s.

 

IOIW, speed increases linearly while distance increases quadratically. It's pointing out that a = dv/dt, not dv/dx. In a world before Newton, one might be tempted to think the latter might be true and insist on that because of logic or other philosophy. Galileo is pointing out that it's wrong.

[cyruseternity]

Xactly wat i was trying to ask....thanks a lot...