2. An object attached to the end of a string swings in a vertical circle (R = 1.2 m), as shown. At an instant when θ = 30°, the speed of the object is 5.1 m/s and the tension in the string has a magnitude of 20 N. What is the mass of the object?


(A) 2.8 kg
(B) 3.5 kg
(C) 4.8 kg
(D) 1.2 kg
(E) 0.4 kg

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