SHM question (1 Viewer)

dathat · Sep 29, 2015

A point moving with simple harmonic motion starts from a point 5 cm from the centre of the motion with a speed of 1 cm/s. The period is 8 seconds. What is the maximum acceleration?

A) 4.9
B) 5.2
C) 24.4
D) 25.6

Could anyone help me with this question plsss

braintic · Sep 29, 2015

$Use the formulae:$

$$Period $=\frac{2\pi}{n}$

$v^2=n^2\left(a^2-x^2\right)$

$\ddot x=-n^2 x$

$$Along with the fact that the maximumum acceleration occurs at $x=\pm a.$

dathat · Sep 29, 2015

braintic said:
$Use the formulae:$

$$Period $=\frac{2\pi}{n}$

$v^2=n^2\left(a^2-x^2\right)$

$\ddot x=-n^2 x$

$$Along with the fact that the maximumum acceleration occurs at $x=\pm a.$

Hey braintic, thank you for your reply but i tried applying everything you provided but kept getting answers not in the MC options.

I kept getting -2.98 a lot.

braintic · Sep 29, 2015

dathat said:
Hey braintic, thank you for your reply but i tried applying everything you provided but kept getting answers not in the MC options.

I kept getting -2.98 a lot.

I don't get any of the answers either.

$\frac{2\pi}n=8$
$n=\frac{\pi}{4}$

$1^2=\left(\frac{\pi}{4}\right)^2\left(a^2-5^2\right)$
$\frac{16}{\pi^2}=a^2-25$
$a^2=\frac{16+25\pi^2}{\pi^2}$

$Ignoring negative:$

$\ddot x_{max}=n^2 a$

$=\frac{\pi^2}{16}\cdot \frac{\sqrt{16+25\pi^2}}{\pi}$

$=3.18$

I do get 5.2 before multiplying by pi^2/16.
So not sure if I have made a mistake or there is a mistake in the question.

SHM question (1 Viewer)

dathat

New Member

braintic

Well-Known Member

dathat

New Member

braintic

Well-Known Member

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