Radial and Tangential Acceleration Question

[physicsguy98]

A ball tied to the end of a string 0.5 m in length swings in a vertical circle under the influence of gravity. When the string makes an angle of 20 degrees with the vertical, the ball has a speed of 1.5 m/s. Find the tangential component of acceleration at this instant. Help!




Tangential Acceleration = dv/dt


I could figure this out but I can't figure out the velocity function. HELP me please!

 

[Doc Al]

What forces act on the ball? What tangential force acts on the ball?