Maximum kinetic energy of a pendulum

[jforce93]

Homework Statement

Okay, so I'm using the online Giancoli physics thing for AP Physics C summer work (see: "([PLAIN]http://wps.prenhall.com/esm_giancoli_physicsppa_6"[/URL]. I think my way of doing it is correct, but the online checker says I'm wrong.
The question: "A pendulum has a mass of 3.2 kg, a length of 1.5 meters, and swings through a (half)arc of 17 degrees. To the nearest tenth of a Joule, what is its maximum kinetic energy of the pendulum?"

Homework Equations

PE = mgh
KE = 1/2mv^2

The Attempt at a Solution

Find the PE of the pendulum. The height of it at 17 degrees: .43856 meters (about).
PE = 3.2*9.81*.43856 = 13.767 Joules. But the online checker says 2.1 Joules.

What am I doing wrong? Or, am I doing it right, the online thing is just wrong?

Thanks,

Jordan

 

[gneill]

Your height for the pendulum bob is not correct.