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(h) How is resultant different from equilibrant ?
(i) State Lami’s theorem and its limitations.
(j) State any four laws of friction.
(k) Define limiting friction.
(l) State the velocity ratio for worm and worm wheel and explain the terms
Attempt any FOUR of the following :
(a) For a certain machine, the law is P = (0.09 W + 6) N. Calculate the effort
required to lift a load of 6 kN. Also calculate maximum M.A. and
identify the type of machine if velocity ratio of the machine is 20.
(b) A load of 1400 N can be lifted by an effort of 40 N in a differential axle and
wheel. The diameter of wheel is 40 cm and diameters of axles are 10 cm
and 8 cm. Find efficiency and effort lost in friction of the machine.
(c) The diameters of bigger and smaller pulleys of Weston’s differential
pulley block are 250 mm and 100 mm respectively. Determine the effort
required to lift a load of 3 kN with 80% efficiency.
(d) Resolve the following forces into its orthogonal components :
(i) 25 kN force inclined at 140° with positive X-axis and acting
towards the point.
(ii) 400 N force acting due south.
(e) A man pulls a hand roller on a cricket pitch and in doing so, exerts a pull
of 150 N inclined at an angle of 30° to the horizontal. Find the force
tending to move the roller forward. If μ = 0.30, find weight of roller.
(f) State any four properties of couple with examples.