FAQ  Donate 
Members List  
Calendar  
Search  
Today's Posts 
LPF Laser Pointer Company Database 

LPF Database of Laser Pointer Companies 
 LinkBack  Thread Tools  Display Modes 
09022010, 04:57 AM  #1  
 
Class 2 Laser Join Date: Sep 2009 Location: 0,0,0 U (dimensions)
Posts: 432
Rep Power: 16 
Well I just started college full time (doing 13 credit hours,) and I decided to take precalculus 2. It's basically just precalculus. I guess part 2 is being considered as precalculus + trigonometry or something. Anyway, I have had this assignment to do with measuring a ball's height drop to it's bounce height. And then make a model for it. It's supposed to be either a power regression or a exponential regression model. I used a little rubber ball that is probably 1 1/2" in diameter. The reason I chose a small ball is to cut out air friction for the most part. (maybe I should have kept air as a larger factor to make it less linear. read on to understand) The reason I'm posting this is that after getting data points (15 different height drops) and plotted it out, it was almost linear. I was wondering if I was getting valid measurement points. The way I look at it is if there was no friction at all, the ball's elasticity was perfect, the bouncing plane absorbed no energy, and gravity (or any force for that matter) was perpendicular with the bouncing plane, the function would simply be f(x) = x (linear with slope of 1). Where x could be height dropped and f(x) would be bounce height. So in other words, the ball would bounce to where it was dropped from as the height it is dropped from is it's potential energy, and it takes the same amount to return back. Of course this is will all energy conserved within the motion of the ball. Though in reality as I get my measurements, there is friction all about it's motion, including the ball it self. So I guess my question is, should my data be "linear" to my accuracy of calculations considering my environment? Environment: ball size: 1 1/2" ball mass: not sure, but it's about equal to the mass of 57 large gum balls. dropping distance minmax: 2"75" surface: hard finished wood (does not absorb much energy) I was thinking if I were to scale up 2"75" that maybe I would start to see something less "linear". Anyway, with my environment, the ball seems to bounce ruffly at 72% it's drop height, regardless of height. This is what I believe keeps it linear. So, am I thinking correctly here? I no I'm totally over thinking it as my instructor really just wants us to get data points and just model it, but I would like to clarify this for myself.
__________________ Optotronics RPL532260  Avg ~294mw GLP532 CNI Pen, From Glenn ~135mw Modded 5mw532 WickedLasers Core ~15mw  Back down to 5mw for fun 532nm Safety Glasses >2 OD ~2.6 OD, From Glenn Defining the undefined defines a new definition of which has always been defined.  
09032010, 03:11 AM  #2  
 
Class 4 Laser Join Date: Sep 2007 Location: Wisconsin
Posts: 8,852
Rep Power: 1363 
Yes, it would be linear. After a great height, however, the peak speed would be closer and closer to terminal velocity, so it would be technically logarithmic when considering air resistance. But with most (all?) physics problems, we assume many factors to be insignificant.
__________________ A problem well stated is a problem half solved.  
09052010, 09:04 PM  #3  
 
Class 2 Laser Join Date: Sep 2009 Location: 0,0,0 U (dimensions)
Posts: 432
Rep Power: 16 
Ok. Thanks for the clarification, Cyparagon. I tried +rep on you, but I have to "spread" more rep first, as the forum says. Oh well, maybe another time.
__________________ Optotronics RPL532260  Avg ~294mw GLP532 CNI Pen, From Glenn ~135mw Modded 5mw532 WickedLasers Core ~15mw  Back down to 5mw for fun 532nm Safety Glasses >2 OD ~2.6 OD, From Glenn Defining the undefined defines a new definition of which has always been defined.  
Thread Tools  
Display Modes  
 