Machine Design Multiple Choice Questions on “Coefficients of Flywheel & Solid Disk Flywheel”.
1. Calculate the coefficient of fluctuation of speed if maximum speed is 2500rpm and minimum speed is 1800rpm.
a) 1.44
b) 1.33
c) 0.33
d) 0.44
Answer: c
Clarification: C=2[(Max-Min)/(Max+Min)].
2. Calculate the coefficient of steadiness if maximum speed of flywheel is 2500rpm and minimum speed is 1800rpm.
a) 3.03
b) 0.33
c) 0.44
d) 3.99
Answer: a
3. Calculate the mean torque T supplied by motor (Torque vs. theta graph of a flywheel is shown above).
a) 3000N-m
b) 1500N-m
c) 2000N-m
d) 2500N-m
Answer: b
Clarification: T[1000+2000/2]x2π/2π.
4. The point where angular velocity is maximum is?
a) A
b) B
c) C
d) D
Answer: c
Clarification: The flywheel is decelerated in the portion BC and hence rpm is least at C.
5. The point where velocity of flywheel is maximum is
a) A
b) B
c) C
d) D
Answer: b
Clarification: Flywheel is accelerated in the portion AB and hence velocity is maximum at B.
6. Calculate the energy output from flywheel.
a) 500π
b) 150π
c) 200π
d) 250π
Answer: d
Clarification: U=Area of ΔBCD as max and min velocities are at B and C.
7. Torque vs. theta graph of a flywheel is shown. Coefficient of fluctuation of speed is 0.2 and the mean angular velocity of the machine is 25 rad/s. Thickness of flywheel is 20mm and density of steel used is 7700kg/mᵌ.
Calculate the outer radius of the flywheel.
a) 402mm
b) 202mm
c) 540mm
d) 468mm
Answer: a
8. Calculate the energy at point B if energy assumed at point A is U.
a) U
b) U-300
c) U+300
d) U-150
Answer: b
Clarification: Simple addition of energy.
9. Calculate the energy at point C if energy at point A is U.
a) U-550
b) None of the listed
c) U+550
d) U+550
Answer: c
Clarification: E=U-300+ 850.
10. Calculate the energy at point F if energy at A is u.
a) U+340
b) U+260
c) U+400
d) Can’t be determined
Answer: c
Clarification: E=U-300+850-500+900-550.
11. Calculate the maximum energy.
a) U+1000
b) U+950
c) U+630
d) U+600
Answer: b
Clarification: Maximum energy is at E. E=U-300+850-500+900.
12. Calculate the point of minimum energy.
a) U+480
b) U+650
c) U-300
d) U-450
Answer: c
Clarification: Minimum energy is at B. E=U-300.
13. Calculate the net energy output from the flywheel.
a) 1300mm²
b) 1400mm²
c) 1250mm²
d) 1500mm²
Answer: c
Clarification: Maximum energy at E[U+950] and minimum at B[U-300]. Thus net energy=[U+950]-[U-300].
14. Feather key can be used to prevent axial motion between two elements.
a) True
b) False
View Answer
Answer: b
Clarification: All types of key but feather key can be used to prevent axial motion between two machine elements.
15. Keyed joints never lead to stress concentration on shafts.
a) True
b) False
Answer: b
Clarification: Keyway results in stress concentration in the shaft and makes the part weak.