A tether ball of mass 0.15 kg is attached to a vertical pole by a cord 1.1 m long. Assume the cord attaches to the center of the ball. If the cord makes an angle of 20° with the vertical, then(adsbygoogle = window.adsbygoogle || []).push({});

a) What is the tension in the cord?

b) What is the speed of the ball?

Ok well i started it. On my free body diagram i only have two forces, the force of gravity (mg sin (theta)) and the force of tension (T). I calculated the radius of the circle the ball travels to be r=.3762 m. My prediction is that mg sin (theta) - T = ma. centripital acceleration is a=v^2/r. However i have one equation with 2 unknowns here. I somehow need to figure out v, or T. Is there another force that I forgot about in the free body diagram?

Thanks

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# Homework Help: A tether ball on pole

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