how to find the distance traveled by an object moving in sinosoidal motion?

magomago

Lifer
Sep 28, 2002
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i have a functionn x(t)=Asin(wt) where w=squiggly w and t=time and a=amplitutde

and i found the max velocity it'll have and when that will occur, the max acceleration and when that'll occur, but i can't figure out how to find the distance covered (not the displacement)

does anyone know? I've been staring at the ansewr and all it goes "...since t=2/3 seconds and amplitude=2 then the distance covered in T is 8 cm. so 8cm + 4 cm = 12 cm" and i'm like "huh?"

I know it isn't difficult...but I don't remember i'm missing~

my amplitude is 2cm and my frequency is 1.5Hz~ if anyone could help me out i'd appreciate it~
 

raptor13

Golden Member
Oct 9, 1999
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Arc length can be calculated as follows:

Take the definite integral from A to B of sqrt(f'(x)^2 + 1). It's as simple as that. f'(x), or f'(t) in your case, is just Awcos(t). Square that and you have ((Aw)^2)*cos(t)^2. Add one. Integrate over your range of t (which is 0 to 1, it sounds like) and you've got your answer. Good luck, though, because that integral will be a pain without a calculator or Matlab or something. There is no elementary anti-derivative that I know of.

Hopefully that helps.
 

magomago

Lifer
Sep 28, 2002
10,973
14
76
hrmm i'm supposed to be able to do this with just a scientific calculator (and evne then our professor prefers us to learn how to round~ ie use 10.0m/ses for g if we are just doing rough estimations, etc.)
 

MetalMat

Diamond Member
Jun 14, 2004
9,687
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Just use your tables in the back of your calculus book, then substitute the constants into the problem. You already know your time and amplitude, should be a cake walk with a scientific calculator.
 

memo

Golden Member
Jul 16, 2000
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by the way squiglly w is probably omega :) i haven't seen this stuff since sophmore year though so i probably wouldn't be much help