A 8.00-kg object swings rapidly in a complete vertical circle of radius 1.00 m b
ID: 1598997 • Letter: A
Question
A 8.00-kg object swings rapidly in a complete vertical circle of radius 1.00 m by a light string that is fixed at one end. The string is always taut and perpendicular to the velocity of the ball. As the ball swings from its lowest point to its highest point
the work done on it by gravity is -118 J and the work done on it by the tension in the string is
zero.
the work done on it by gravity is zero and the work done on it by the tension in the string is
+118 J.
the work done on it by gravity and the work done on it by the tension in the string are both
equal to -157 J.
the work done on it by gravity is -157 J and the work done on it by the tension in the string is zero.
the work done on it by gravity is -118 J and the work done on it by the tension in the string is
zero.
the work done on it by gravity is zero and the work done on it by the tension in the string is
+118 J.
the work done on it by gravity and the work done on it by the tension in the string are both
equal to -157 J.
the work done on it by gravity is -157 J and the work done on it by the tension in the string is zero.
Explanation / Answer
Work done by gravity = raise in potential energy = mgh = mg(2r) = 8(-9.8)(2(1)) = - 157 J.
Work done by tension = zero since the angle between Tension and the displacement is always 90o in a vertical circle.
Hence the correct option is last option.
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