(a) State two; (i) laws of solid friction; (ii) advantages of friction; (iii) methods of reducing friction. (b) Draw and label a diagram of a pulley system ...

(a) State two;

(i) laws of solid friction;

(ii) advantages of friction;

(iii) methods of reducing friction.

(b) Draw and label a diagram of a pulley system with velocity ratio of 5.

(c)(i) Show that the efficiency L, force ratio M.A. and the velocity ratio V.R. of a machine are related by the equation \(E =  \frac{M.A.}{V.R}\)  x 100%. 

(ii) The efficiency of a machine is 80%. Calcuate the work done by a person using the machine to raise a load of 300 kg through a height of 4 m.[ g = 10 ms\(^{-2}\) ]