82.

88.

87.

88,

1
Answer ALL questions. Answer shall be limited to one paragraph.
Questions 31 to 38 carry 10 marks ೧೩೦೫,

A leather belt 9 mm = 250 mm is used to drive a cast iron pulley 900 mm in diameter at 336
rpm. If the active arc on the smaller pulley is 120° and the stress in tight side is 2 MPa, find
the power capacity of the helt. The density of leather may be taken as 980 kg/m® and the
coelficient of friction of leather on 086% 107 15 0.35.

A component is subjected to completely reversed stress cyele which varies over a 30 second
time period, as follows :

10 eycles at 500 MPa
5 eycles at 600 MPa
3 eycles at 700 MPa

The corresponding fatigue lives for the above stresses are 10%, 4:10* and 15 »10* ೮0105
respectively. Datermine the fatigue life of the component. '

A Diesel engine has a compression ratio of 14 ಜಾರ cut-off takes place at 6% of the stroke, Find
the air standard efficiency.

A 400 kg diesel engine mounted ता a chassis frame runs at 500 rpm. The static deflection of
the weigh iz 2.4 mm. The reciprocating parts have a mass of 18 kg. The stroke of the engine
is 160 mm. The damping coefficient of the dash pot attached is 2 N/mm/s. Determine the
amplitude at steady state and the resonance speed

A cantilever of length 7', moment of inertia ‘T and Young's modulus ‘% carries a coneentrated
load Wat the middle of its length. Calculate the slope of the cantilever at the free end.

A person of mass 80 kg and another person of 60 kg stand side by side at the same end ofa
130 kg boat, ready to dive each with a velocity of 5 m/s relative to the boat. Determine the
velocity of the boat after they have both dived, Assume that the 80 kg ணம்‌

A boiler produces 2000 kg of dry and saturated steam per hour at 10 bar and feed water is
heated by an economizer to a temperature of 110°C. 225 kg coal of a calorific value of
30100 kd/kg are fired per hour. If 10% of coal remains unburnt find the thermal efficiency of
the boiler. Enthalpy of dry saturated steam at 10 baris 2776.2 k J/ ke.

A damped vibrating system consists of a mass of 8 kg which makes 30 oscillations in
18 seconds. After 5 oscillations, the amplitude reduced to 0.25 times the initial value.
Determine the spring stiffness, logarithmic decrement, damping coefficient and damping
factor.

6 ⋅ 78/2015