Answer:
The answer should be 36 Joules.
Explanation:
This can be solved as a angular motion.
Angular velocity w = V/r
Where V is the linear velocity 6 m/s
And r is the radius of rotation which is equal to the lenght of the string 0.8 m
w = V/r = 6/0.8 = 7.5 rad/s
Moment of inertia of rotation I = mr^2
Where m is the mass of the ball 2 kg
I = 2 x 0.8^2 = 1.28 kg-m2
From energy conservation, work done is equal to the kinetic energy of the angular motion.
KE = 0.5Iw^2
= 0.5 x 1.28 x 7.5^2 = 36 Joules.
