Answer:
v = 16.49 m/s
Explanation:
Given that,
Length of the string, l = 1.15 m
The ball makes 137 complete turns each minute.
We know that, 1 turn = 6.28 rad
137 turns = 860.79 rad
1 min = 60 s

We need to find the tangential velocity of the ball. It can be given by

So, the tangential velocity of the ball is 16.49 m/s.
I think that building on a green hill
Hmm.... Oxygen support combustion. Other than that, rusting occur when oxygen is combined with metal. When iron rusts, it combines with oxygen. Hope it helps.