Pendulum swing angle

1. Oct 30, 2012

phunphysics2

I was wondering if somebody could please check my work for the problem below.

A pendulum with a length 2m has a velocity of 3 m/s at its lowest point. What is the largest angle it creates relative to the horizontal as it swings. Hint: use energy conservation.

Here is my work
mgh=mv^2/2,,,,,,,,,,h=0.459 m,,,,,,,,,cos(angle) = h/r=0.459/2,,,,,,,,,,,angle=76.7 degree

Please let me know if it is correct. If it is wrong, please give suggestions on how I should correct.

Thanks!
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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2. Oct 31, 2012

grzz

The value of h is ok.

But note that cos(angle) = (r - h)/r

3. Oct 31, 2012

phunphysics2

But I am not sure that I understand what you mean

4. Oct 31, 2012

grzz

Refer to the diagram attached.

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5. Oct 31, 2012

phunphysics2

Thank you for the diagram! so cos (angle)= (2-.459)/(2)