A certain cord will break if its tension exceeds 250 N. Suppose the cord is attached to a 0.50 kg ball. If the ball is swung in a horizontal circle at the end of a 0.80 m cord, how fast can the ball move before the cord breaks?

T = mv^2/r

Plug in the maximum tension force to get the fastest speed of the ball.

250 = 0.50(v^2)/0.80

Solve for v,

v = sqrt(400) = 20 m/s <==Answer