A shaft has an attached disc at the centre of its length. The disc has its centre of gravity located at a distance of 2 mm from the axis of the shaft. When the shaft is allowed to vibrate in its natural bow-shaped mode, its has a frequency of vibration of 10 radians/secon(d) When the shaft is rotated a 300 revolutions per minute, it will whirl with a radius of
(a) 2 mm (b) 2.25 mm
(c) 2.50 mm (d) 3.00 mm