Simple Harmonic motion question (1 Viewer)

[noobonastick]

Hi, what's the difference between the general formulas : b + acos(nt + alpha ) and b + asin(nt + alpha) when do I use either one. Please provide an example.

 

[kwabon]

Hi, what's the difference between the general formulas : b + acos(nt + alpha ) and b + asin(nt + alpha) when do I use either one. Please provide an example.

doesnt matter what you start off with, both are basically the same thing.

 

[bv]

dont rely on my answer, i am not sure either but i think u use the cos when it starts at the ends and sin at the equilibream its prob way off just feel like having a punt

 

[kwabon]

dont rely on my answer, i am not sure either but i think u use the cos when it starts at the ends and sin at the equilibream its prob way off just feel like having a punt

dont matter, even if it does start at the equilibrium, you could just use cosine with a phase shift (hence the "alpha"). will be a little harder but will not make a overall difference to your answer.

 

[jet]

Cos and Sin are the same thing, shifted pi/2 apart. Picking one over the other is just a matter of convenience, but it doesn't really matter.

 

[noobonastick]

ok i think i get it, so you would get a different alpha if using sin instead of cos, but its the same equation, its just that one is more convenient in some circumstances.

 

[scardizzle]

putting what jet black said simply

sinx = cos (90 - x)

and vica versa