coefficient of friction, between the block and wall assuming it to be same.

Answer any 2 complete questions each having 10 marks

15. A lift has an upward acceleration of 1.2 m/s”. (a) What force will a man weighting 750 N exerts
on the floor of the lift? (b)What force would he exert, if the lift had an acceleration of 1.2 m/s’
downwards?(c) What upward acceleration would cause his weight to exert a force of 900 N in
the floor?

16. Ina reciprocating engine mechanism the crank rotates at a uniform speed of 400rpm. The length
of crank and connecting rod are 150mm and 600mm respectively. Find (a) the angular velocity
of the connecting rod (b) the velocity of piston when the crank makes an angle of 250 with
horizontal.

17. A body of mass 50 kg is suspended by two springs of stiffness 4 kN/m and 6kN/m as shown in
figure. The body is pulled 50mm down from its equilibrium position and then released. Find (a)

the frequency of oscillation (b) maximum velocity (c) maximum acceleration.

AAAS
4kN/m

50 kg

6kN/m

^.