20. Exercises

A particle, of mass 2 kg, is attached to a fixed point on a smooth horizontal table by a light inextensible string of length 50 cm. The particle travels in a circle on the table at 400 r.p.m. Find the tension in the string.

A marble is made to rotate against the outside rim of a circular tray of radius 0.2 m. The mass of the marble is 100 grams and it moves at 2 \displaystyle \text{m}{{\text{s}}^{-1}}. Calculate the horizontal force that the tray exerts on the marble.