Physics
posted by Camilla .
What is the minimum speed that a 5kg conical pendulum can achieve if its 1 m string has a maximum tension rating of 520 N?
A. 9.5 m/s
B. 10.2 m/s
C. 4.9 m/s
D. 20.2 m/s
E. 12.3 m/s
My solution's manual says the answer is B, how is it the answer?

ma=mv²/R =T•cosα
R= L•cosα
v=sqrt(T•L•cos²α/m)
V(max) at cos α =1 =>
v(max) = sqrt(T•L/m) =
sqrt(520•1/5) = 10.2 m/s