An 10.0 kg ball, hanging from the ceiling by a light wire 125 cm long, is struck in an elastic collision by a 1.20 kg ball moving horizontally at 7.50 m/s just before the collision. Find the tension in the wire just after the collision.
M1V1o + M2V1o = M1V2f + M2V2f
The Attempt at a Solution
(1.2 kg)(7.5 m/s) = (10 kg)(Vf)
Vf = 0.9 m/s
Fc = mV^2/R = (10 kg)(0.9^2)/(1.25 m) = 6.48 N
Fc = T - mg
6.48 = T - (10 kg)(9.8)
T = 104.48 N -- Book says it's incorrect, what am i doing wrong?