So we had this worksheet to do in Physics today. Which read:

With this table at the beginning.

"Example 2.

A pendulum has a bob of mass .15kg. To get it moving with SHM, the bob is pulled aside until it has gaines a height of 0.902m.

1. Calculate the total energy.

2. Calculate the maximum speed."

So first of all I understand the first example. But this second one I'm not entirely sure about. I was going to use 1/2KA^2 for the first question until I realised that didn't work. Then I went ahead and decided that I would use 1/2mv^2 which I realised also wouldent work. My teacher said that for that question we need to use Ep = mgh.

Well how was I supposed to know that when the question says calculate total energy and I have a table of equations with a column of total enery equatins right above which dosen't include that one? And for the second question I'm apparently supposed to use v = √2EK/m

or 1/2mv^2 (which is the one I'm going to use) but I don't understand where v = √2EK/m came from. I swear I have never seen that equtaion before.