a wreacking ball is used to demolish a building. The 600-kg ball starts from rest, with it's 37-m-long cable making a 22 degrees angle with the vertical. it strikes the building when the cable is vertical. What is the speed of the ball on impact?(adsbygoogle = window.adsbygoogle || []).push({});

it doesnt seem like a hard question, but i cant figure it out.

[tex]U_o =mgL(1-cos(\theta))[/tex]

[tex] K_0 = 0[/tex]

[tex]U_f = 0[/tex]

[tex]K_f = 1/2mv^2[/tex]

[tex]mgL(1-cos(\theta)) = 1/2mv^2[/tex]

[tex]V= \sqrt{\frac{gL(1-cos(\theta))}{2}}[/tex]

plugging in known values, i get 3.6 but the book gets 7.3 m/s. am i missing something?

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# Homework Help: Quick energy question

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