Design of Machine Elements MCQ with Answer.

Q.no 51. Which of the following statements is/are true?

1. In volute springs, number of active coils gradually decreases as load increases
2. Stiffness of spring decreases as number of coils decreases in conical springs
3. Torsion springs are generally spiral
4. Helical torsion springs are used in automobile starters
5. 
   A : Statements 1 and 3
   B : Statements 2, 3 and 4
   C : Statements 1, 3 and 4
   D : Only Statements 1

Q.no 52. A leaf spring consists of 3 extra full length leaves and 14 graduated length leaves. The maximum force that can act on the spring is 70kN and the distance between eyes of the spring is 1.2m. Width and thickness of the leaves are 100mm and 12mm respectively. Calculate the initial pre load required to close the nip.

A : 4332.2N
B : 4674.1N
C : 4985.4N
D : Can’t be determined

Q.no 53. Two spring having stiffness constants of 22N/mm and 25N/mm are connected in parallel. They are to be replaced by a single spring to have same effect. The stiffness of that spring will be?

A : None of the mentioned
B : 3N/mm
C : 47N/mm
D : 11.7N/mm

Q.no 54. If shaft diameter is 30mm and number of pins emplaced are 6, then the diameter of the pin will be?

A : 6.4mm
B : 5.6mm
C : 6.1mm
D : 5.9mm

Q.no 55. A leaf spring consists of 3 extra full length leaves and 14 graduated length leaves. The maximum force that can act on the spring is 70kN and the distance between eyes of the spring is 1.2m. Width and thickness of the leaves are 100mm and 12mm respectively. If modulus of elasticity is 207000N/mm², calculate the initial nip.

A : 26.8mm
B : 24.9mm
C : 22.5mm
D : 23.1mm

Q.no 56. According to A.S.M.E code what is the allowable shear stress for a shaft without keyway effect, which has ultimate tensile strength and yield strength of 300 N/mm2 and 150 N/mm2 respectively.

A : 45 N/mm2
B : 54 N/mm2
C : 40.5 N/mm2
D : None of the above

Q.no 57. Determine torque required to overcome collar friction in square threaded screw, if coefficient of friction is 0.12 and axial force of 20 kN is exerted by the screw. Mean radius of friction collar is 20 mm

A : 48000 N-mm
B : 120 N-mm
C : 4800 N-mm
D : 12000 N-mm

Q.no 58. Determine the length of rectangular sunk key required to transmit 1200N-m and allowable shear in the key is 40MPa. The diameter of shaft and width of key can be taken as 40mm and 10mm respectively.

A : 200mm
B : 150mm
C : 180mm
D : 220mm

Q.no 59. Find the torque required to raise the load of 15kN and mean diameter of triple threaded screw being 46mm. Also given pitch=8mm and coefficient of friction is 0.15.

A : 11831.06N-mm
B : 11813.06N-mm
C : 12811.06N-mm
D : None of the listed

Q.no 60. Determine the diameter of the rod in cotter joint subjected to axial load of 50kN and permissible tensile stress in rod is 100MPa

A : 25.23
B : 30.23
C : 21.5
D : 22.21

Answer for Question No 51. is c
Answer for Question No 52. is b
Answer for Question No 53. is c
Answer for Question No 54. is c
Answer for Question No 55. is b
Answer for Question No 56. is a
Answer for Question No 57. is c
Answer for Question No 58. is b
Answer for Question No 59. is a
Answer for Question No 60. is a