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## Homework Statement

A 2.0 kg ball swings in a vertical circle on the end of an 80 cm-long string. The tension in the string is 20 N when its angle from the highest point on the circle is theta = 30.

A) What is the ball's speed when theta = 30?

B) What is the magnitude of the ball's acceleration when theta = 30?

C) What is the direction of the ball's acceleration when theta = 30? Give the direction as an angle from the r-axis.

## Homework Equations

f=ma; a = v

^{2}/r

## The Attempt at a Solution

A) T-mgcos(theta)=mv

^{2}/r; v=sqrt((t-gcos(theta))*r) which is 3.8 m/s (the correct answer)

I have no idea how to go about finding part b and c. The only thing I may know about part c is that I'll have to use arctan at some point.

Thanks for all the help, I really appreciate it :)