Help on Pendulum Homework: A1, A2, & Work Done

[ataglance05]

Homework Statement

1) A pendulum 1 meter in length is pulled back 12.7 degress and the bob has a mass of 1kg. At the moment the bob is released, a)what's the acceleration in m/sec^2 of the bob along the curve of its swing and b)what is the acceleration toward the center of the bob's rotation?

2) For the pendulum in problem 1, how much work was done to pull the pendulum back 12.7 degrees?

Homework Equations

i think... to get the acceleration of bob along the curve of its swing...you use:

and

and a^2+b^2=c^2

The Attempt at a Solution

First, i drew the pendulum/free body diagram:

My teacher said to just get a1, which is the acceleration of the bob along the curve of its swing, and a2, the other acceleration.

a)so...
a1=sin(77.3)=opposite/10
.9755=opposite/10
opposite=9.755

9.755^2+b^2=10^2
b^2=4.84
b=2.2
so a1=2.2m/sec^2

b)a2=cos(12.7)=adjacent/10
.9755=adjacent/10
adjacent=9.755

9.755^2+b^2=10^2
b^2=4.84
b=2.2
soa2=2.2m/sec^2

1) i don't think this is right since I get the same accelerations. please help?? Did i do it all right or can you help me solve this problem??

2) All I know is that I need to use the equation PE=mgh and where m is mass, g is gravitational acceleration, and h is the height and height=L((1-cos(theta)). The only thing I really know how to do is get h sine I'm not sure what is L. How do I get that??[/b] HELP ME!

THANK YOU!

 

[ataglance05]

anyone?