The ball has a mass of 30 kg and a speed of [itex]4\,\frac{m}{s}[/itex] at the instant it is at its lowest point, [itex]\theta\,=\,0[/itex]. Determine the tension in the cord and the rate at which the ball's speed is decreasing at the instant [itex]\theta\,=\,20[/itex]. Neglect the size of the ball. NOTE: The cord length is 4 m.(adsbygoogle = window.adsbygoogle || []).push({});

Here is what I have found so far, the acceleration:

[tex]\sum\,F_t\,=\,-W\,sin\,\theta\,=\,m\,a_t[/tex]

[tex]-m\,g\,sin\,\theta\,=\,m\,a_t[/tex]

[tex]a_t\,=\,-g\,sin\,\theta[/tex]

[tex]a_t\,=\,-\left(-9.81\,\frac{m}{s^2}\right)\,sin\,(20)[/tex]

[tex]a_t\,=\,3.36\,\frac{m}{s^2}[/tex]

I cannot get the right answer for the tension in the cord though. Please help!

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# Tension in a Pendulum Problem - 30kg, 4m cord, 4m/s @ bottom

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