The object takes 0.5 seconds to complete one rotation, so its rotational speed is 1/0.5 rot/s = 2 rot/s.
Convert this to linear speed; for each rotation, the object travels a distance equal to the circumference of its path, or 2π (1.2 m) = 2.4π m ≈ 7.5 m, so that
2 rot/s = (2 rot/s) • (2.4π m/rot) = 4.8π m/s ≈ 15 m/s
thus giving it a centripetal acceleration of
a = (4.8π m/s)² / (1.2 m) ≈ 190 m/s².
Then the tension in the rope is
T = (50 kg) a ≈ 9500 N.
