Shm (1 Viewer)

[Hotdog1]

What equations can you assume for the HSC, eg. Do you have to derive v^2 = n^2 (a^2-x^2) ?

Also when a question ask you to show a particle is under SHM, do you just show its acceleration is equal to -n^2x ?

Thank you.

 

[ND]

What equations can you assume for the HSC, eg. Do you have to derive v^2 = n^2 (a^2-x^2) ?

Yeh you could be asked to show that.

Also when a question ask you to show a particle is under SHM, do you just show its acceleration is equal to -n^2x ?

Yep.

 

[Hotdog1]

Originally posted by ND
Yeh you could be asked to show that.

In a larger question, when you are NOT asked to show this, but this is required as a step, can you just assume the equation, WITHOUT prooving it?

 

[Hotdog1]

stupid forum glitch, not updating posts... *bump*

 

[...]

shit, do u have to show how to get v^2 = n^2 (a^2-x^2)

can someone show me

 

[Lazarus]

Originally posted by Hotdog
In a larger question, when you are NOT asked to show this, but this is required as a step, can you just assume the equation, WITHOUT prooving it?

Yes.

Originally posted by ...
shit, do u have to show how to get v^2 = n^2 (a^2-x^2)
can someone show me

<pre>x = a.cos(nt + c)
v = -an.sin(nt + c)

v² = n²a².sin²(nt + c) squaring both sides
&nbsp;&nbsp;&nbsp;= n²a²(1 - cos²(nt + c)) sin² t + cos² t = 1
&nbsp;&nbsp;&nbsp;= n²a² - n²a²cos²(nt + c) expanding
&nbsp;&nbsp;&nbsp;= n²a² - n²x² as x = a.cos(nt + c)
v² = n²(a² - x²)</pre>

 

[...]

icic...

thx laz...

edit: u forgot "-" when u squared it