A particle of mass 10 kg lies on a rough plane (a) 7. inclined at an angle of 0 to the horizontal, 10 kg where tan 0 = 3 A horizontal force F is applied to the particle to prevent it from slipping. 1 The coefficient of friction between the particle and the plane is 2 Find the value of F, in terms of g. (b) Two equal uniform rods AB and AC, each of length 21 and weight W, are smoothly jointed at A. They rest in equilibrium in a vertical plane with the ends B and C on two smooth planes each inclined at an angle a to the horizontal and |ZCAB|=28. 28 Ends B and C of the rods are connected by a light inextensible string. (i) Show that the tension in the string is (tan- 2 tana]. (ii) Find the value of tan a for which there is no tension in the string, given that the length of the string is 2/21.