# SHM question

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1. Feb 12, 2017

### Faiq

1. The problem statement, all variables and given/known data
Question is provided

3. The attempt at a solution
The required solution is provided

My question is, the examiner have used sine theta in their expression for change in potential. I keep ending up with 1 - cosine theta
Second question is how did they get rid of theta in the proceeding equation

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2. Feb 12, 2017

### Staff: Mentor

See the left side. For small angles, $\sin \theta \approx \theta$ and $\cos \theta \approx 1 - \frac 1 2 \theta^2$ (sometimes $\cos \theta \approx 1$ is sufficient).