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Member warned to use the homework template for posts in the homework sections of PF.

Okay, so I have just started with simple harmonic motion(SHM).

So the equation of displacement in my text book is given as:

X= A

where A is the amplitude

X is displacememt from mean position at time t

w is angular frequency

x is phase constant.

Everything going good till now, then comes an illustration where suddenly the equation becomes:

X= A

where A is the amplitude

X is displacememt from mean position at time t

w is angular frequency

x is phase constant.

and then onwards in most of the sums they solved with the sin equation and not cos.

I dont get which equation to use when, how and why?

I know every Sin function can be expressed in terms of cos and vice versa, also every SHM is either in the form of Sin or Cos.

But I cant figure out which one to use and why and when.

One observation i made- usually in case of linear SHM about X axis, cos equation is used and in case of linear SHM about y axis, sin equation is used. I used the word usually beacuse that was not the case everytime. Also i dont think this can be a logic as its upto me which one will i take as X axis and which one y if its just a linear SHM.

Someone please help!!!!!!!

So the equation of displacement in my text book is given as:

X= A

**(wt +x)**__Cos__where A is the amplitude

X is displacememt from mean position at time t

w is angular frequency

x is phase constant.

Everything going good till now, then comes an illustration where suddenly the equation becomes:

X= A

**(wt +x)**__Sin__where A is the amplitude

X is displacememt from mean position at time t

w is angular frequency

x is phase constant.

and then onwards in most of the sums they solved with the sin equation and not cos.

I dont get which equation to use when, how and why?

I know every Sin function can be expressed in terms of cos and vice versa, also every SHM is either in the form of Sin or Cos.

But I cant figure out which one to use and why and when.

One observation i made- usually in case of linear SHM about X axis, cos equation is used and in case of linear SHM about y axis, sin equation is used. I used the word usually beacuse that was not the case everytime. Also i dont think this can be a logic as its upto me which one will i take as X axis and which one y if its just a linear SHM.

Someone please help!!!!!!!