A certain cord will break if its tension exceeds 360 N. Suppose the cord is attached to a 0.40 kg ball. If the ball is to be swung with a speed of 25 m/s, what's the shortest length of cord that can be used?

## What's the shortest length?

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# 2 Answers

Sun, just as in the cornering problem this is a rotational acceleration and force problem.

F= m v

^{2}/r, but this time we want to solve for r given a mass, velocity and maximum force.rearranging the equation:

r= mv

^{2}/F , given the values in the problemr

_{min}= (.4)(25^{2})/360 = .6944 metersT = mv^2/r

Plug in the maximum tension force to get the shortest length of the cord.

360 = 0.40(25^2)/r

Solve for r,

r = 25/36 = .69 m <==Answer