help with SHM (1 Viewer)

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hey guys, i got a SHM test this friday and i got this q i wanna ask...


note: =alpha
for the general form of a displacement of particle moving in SHM, the formula is x=acos(nt+) where a,n and are constants. The question is, what does mean and can someone do a example question to show me....coz majority of questions i do, =0 and that comes from teacher telling me without saying why.

thanks a lot in advance

 

[McLake]

SHM is of the form x=acos(nt+) (or x=asin(nt+)) beacuse it describes perodic "wave" motion. If this motion starts from a mean postion (such as x = 0) or from the max postion then =0. This is beacuse it fits the standard sin/cos curve. Other values of will give you different starting postions on the curve. So you would use it if you started at a different postion (like x=1 lets say).

Does that make sense?

 

[underthesun]

in other words, that is just for "adjusting" the motion graph to the desired position, according to the conditions that you'll be given.

If you see the sin graph and cos graph, that basically moves the graph left and right, when you increase or decrease it. get a graph calculator and you'll see why

it doesn't change anything, it just adjusts the graph.

 

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i think i get it now...so how do i work out the value of , or will it be given???

 

[McLake]

You will either be given it, or you will be given enough information to work it out.

 

[kass]

If it's in the form acos(nt+), then it will be fairly easy to work out, otherwise I don't think it will matter too much, because it doesn't change the amplitude or anything like that.

 

[PoLaRbEaR]

It indicates the shifting of the graph...u can see it when u graph y=(x)^2 and y=(x +1)^2. You'll notice that its the same graph as y=(x)^2 except that its shifted to the left - same concept with trig...