MPPSC Question 2017 Paper- I

(A) A hollow circular bar of outside diameter  twice the  inside  diameter  is used as a beam. The bar is subjected to bending moment of 40 kN m. If the allowable bending stress in the beam is to be limited to 100 MN/m 2 , find the inside diameter of the bar.

(B)Make a list of six principal theories of failure. Explain major consideration and  application  of maximum  principal stress theory.

(C)A flat bar 32 mm wide and 12 mm thick is loaded by a steady tensile load of 85 kN. The material is mild steel with yield point stress of 315 N/ mm2 .Find  the  factor  of safety based  on the yield point.

(D)Design the longitudinal joint for a 1-25 m diameter steam boiler carrying a steam pressure of 5  N / mm‘. The allowable  stress of  the  plate  material  is 80 N / mm 2 in tension. Length of the shell of boiler is 5 m. Take allowable stress for  shielded  arc  weld = 95  N / mm 2 .

(E) Find the length of belt (open and cross) necessary to drive a pulley of 80 cm diameter running parallel at a distance of 12 m from  the  driving  pulley  of diameter  480 cm.

(F)Make a list of various types of gear trains. Derive an expression for ve1ocity ratio  of  a  simple gear train.

(G)A uniform  disc of  diameter  30 cm  and  weighing  5  N is  mounted  on one end of an arm of length 60 cm. The other end of the arm is free  to  rotate  in a universal   bearing.   If   the     disc   rotates   about   the   arm   with   a   speed   of 300  r.p.m. clockwise, looking from the front, with wb.at speed will it precess about  the vertical axis ?

(H) For  what  type  of  materials  ultrasonic  machining  (USM)  is  best  suitable process of material removal ?  Make  a  sketch  showing  major  parts  of  USM setup.

(I) Classify comparators. Explain the working and constructional details of any one comparator.

(J) For a small project with five jobs, the following data is given :

 JOB Immediate Predecessors Duration (days) Mean STD. deviation A - 10 2 B - 5 1 C A 16 2 D A 12 2 E B,C 15 1

(i)
Draw the project network in activity on arc mode.

(II)     Under   PERT   assumptions,   determine   the    distribution    of    project duration.

SECTION   A

Attempt at least one question

7. (A) Calculate the fundamental deviation and tolerances and hence the limits of size for the shaft and hole for the following fit :

60 mm H7-f8

The diameter steps are 50 mm and 80 mm.

(B) A television repairman finds that the time spent on his jobs has an exponential distribution with a mean of 30 minutes. If he repairs sets in the order in which they came in, and if the arrival of sets follows a Poisson's distribution approximately with an average rate of 10 per 8-hour day, what is the repairman's expected idle time each day? How many jobs are ahead of the average set just brought in?

(C) A cantilever member 0-1 m long having cross-section of 0-05 mxO-25 m supports a load of 27.5 kN. What is the maximum shear stress and where does it occur?