# Physics

posted by Physics: Circular Motion?

A ball (m = 250g) on the end of
string swings in 1.2 m radius that tolerates 20 N. At what speed does the string breaks if
a) the rings swings horizontally ?
b) the rings swing vertically?

I think I got a) right:
T=mv2/r ---> v=(sqr)Tr/m

v=(sqr) 20x1.2/0.25= 9.8 m/s

Given answers are: 9.8 m/s and 9.2 m/s

Can someone help me how to find maximum speed when the rings swings vertically please ? :)

1. Damon

Max force at bottom = 20 = m v^2/r + m g

20/.25 = v^2/1.2 + 9.81

v^2 = 70.19 *1.2 = 84.2

v = 9.17 m/s

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