Help desperately shm. (1 Viewer)

[Smilebuffalo]

Hey guys.

So i'm kinda.. completely lost for Simple Harmonic Motion. I completely dozed off during the week that it was being taught and now that school is already over i can't ask my teacher for help.

I've read some textbooks and they sort of gave me an idea, but i still don't have a firm understanding of SHM.

Does anyone have any good notes or sample questions on the topic?

Or can someone please post on how to do SHM questions...?

Help much appreicated !

 

[ninetypercent]

I don't have any questions You could take a look at some past papers. Simple Harmonic Motion scares me, too. I skipped it because it looked daunting. I decided to work on Polynomials instead

 

[Smilebuffalo]

lol i'm in dire need of help. sitting HSC this year for 3unit as an accelerant and i haven't learnt SHM yet T_T

 

[Trebla]

The theory involved in SHM isn't actually particularly hard. You just have to understand how to use it in a problem.

It's formal definition is simply the acceleration is proportional to displacement by a negative number. All you need to know is that SHM is a type of motion which behaves like a wave, hence can be described as a general sine or cosine curve. You also have to know where the acceleration or velocity is at min, zero or max (you can easily see this by examining/graphing the first and second derivatives of the trig functions).

The rest is simply normal applications of calculus to the physical world type problems on SHM (e.g. find where it rests and what what time etc...) with calculus and algebra. So if you understand what SHM actually is, you'll find that the questions you get asked are no different to the ones you get in normal velocity/acceleration type problems, they just use different equations but are exactly the same ideas.

 

[scardizzle]

The most difficult SHM questions ive seen are the tide ones, where the questions gives you the time for high tide and low tide and a ship can only make it out of the harbour at a certain heigh and you have to formulate your own equation and work out the time period for the ship to be able to leave the harbour.

So be sure to know the general equations for SHM:

x = acos(nt + e) + b

or =asin(nt + e) + b

v^2 = n^ 2(a^2 + (x-b)^2)

a = -n^2x

also be wary of certain questions where you have to use the r transformation to get x = f(x) into one of the general form

it also helps to draw a diagram with these kinds of questions so you can sort of see if the answer you have is completely wrong