P. 4158. A uniform solid disc of radius 10 cm and of mass 5 kg is rotated at an angular speed of 120 1/s along its horizontal symmetry axis, and carefully, without giving any initial speed to it, it is placed to a horizontal surface. The coefficient of friction between the disc and the surface is 0.4.
Determine the work done by the frictional force on the disc, while it covers a distance of 5 m:
a) with using the definition of work done;
b) with using the work-energy theorem.
(Neglect air resistance and rolling friction, and calculate with g=10 m/s2.)
Deadline expired on 11 May 2009.