Balancing of Rotating Masses topics include: Balancing several masses rotating in planes, balancing of rotating masses and single rotating masses in same and different planes. Balancing rotating masses is an engineering process that involves distributing mass in a rotating body to reduce vibration and improve performance.  Balancing rotating masses can be accomplished using either static or dynamic balancing techniques. Static balancing: Involves adding weight to the machine to balance the forces generated by the rotating masses. Static balancing is typically done by adding weights to the... Show more

Balancing of Rotating Masses topics include: Balancing several masses rotating in planes, balancing of rotating masses and single rotating masses in same and different planes.

Balancing rotating masses is an engineering process that involves distributing mass in a rotating body to reduce vibration and improve performance. 

Balancing rotating masses can be accomplished using either static or dynamic balancing techniques.
Static balancing: Involves adding weight to the machine to balance the forces generated by the rotating masses. Static balancing is typically done by adding weights to the outside of the rotor. A rotating mass is said to be statically balanced if the rotating mass can rest without turning, at any angular position in its bearings.
Dynamic balancing: Involves adding or removing weight from the rotating parts to achieve a balanced state. Dynamic balancing is often synonymous with rotor balancing. Dynamic balance is related to a rotating object in motion. When an object is dynamically balanced, it remains balanced even when it's turning. 

Unbalanced rotating masses can cause serious damage to machinery, which can result in production delays and even accidents. 

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Machine Dynamics Practice Test: Balancing of Rotating Masses

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25 Questions

1. Let the disturbing mass be 200 kg and the radius of rotation be 20 cm and the rotation speed be 50 rad/s, then calculate the centripetal force in kN.

-50-2500-25-100

2. Unbalanced mass leads to vibrations.

FalseTrueMaybeDon't Know

3. Let the centrifugal force in kN be 25 and the radius of rotation be 20 cm and the rotation speed be 50 rad/s, then calculate the mass defect in Kg.

50000502525000

4. Balancing of reciprocating masses is the process of providing the second mass in order to counteract the effect of the centrifugal force of the first mass.

TrueDon't KnowMaybeFalse

5. A single mass defect needs to be balanced by a single balancing mass

MaybeDon't KnowTrueFalse

6. The mass used to balance the mass defect is known as ______

Fixing massBalancing massDefect massReplacement mass

7. Which of the following statements are associated with complete dynamic balancing of rotating systems?
1. Resultant couple due to all inertia forces is zero.
2. Support reactions due to forces are zero but not due to couples.
3. The system is automatically statically balanced.
4. Centre of masses of the system lies on the axis of rotation.

2, 3 and 4 only1, 2, 3 and 41, 3 and 4 only1, 2, and 3 only

8. In the given figure, m₁=10, Kg m₂=30Kg and m=50 Kg, if r₁=0.2m and r=0.3m, l=1m, find l₂.

0.13m0.26m0.52m1.04m

9. In a revolving rotor, the centrifugal force remains balanced as long as the centre of the mass of the rotor lies ___________

On the axis of the shaftAway from the axis of shaftBelow the axis of shaftAbove the axis of shaft

10. Centrifugal force acts radially inwards and bends the shaft.

Don't KnowMaybeFalseTrue

11. Let the disturbing mass be 100 kg and the radius of rotation be 20 cm and the rotation speed be 50 rad/s, then calculate the centrifugal force in kN.

50250002550000

12. The effect of hammer blow in a locomotive can be reduced by ______________

decreasing the speed and using two or three pairs of wheels coupled togetherbalancing whole of the reciprocating partsdecreasing the speedusing two or three pairs of wheels coupled together

13. Multi-cylinder engines are desirable because

only balancing problems are reducedonly flywheel size is reducednone of theseboth (a) and (b)

14. From the given data, find the balancing mass’s inclination in degrees if r=0.2m required in the same plane.
Masses = 200kg, 300kg, 240 kg, 260Kg, corresponding radii = 0.2m, 0.15m, 0.25m and 0.3m.
Angles between consecutive masses = 45, 75 and 135 degrees.

201.48210.34200.32202.88

15. If the rotation speed of the shaft increases then the balancing mass must also increase.

TrueFalseMaybeDon't Know

16. What is the effect of a rotating mass of a shaft on a system?

Bend the shaftExtend the shaftTwist the shaftCompress the shaft

17. Balancing of single rotating mass by balancing masses in same plane and in different planes cannot take place.

MaybeFalseDon't KnowTrue

18. If all the masses are in one plane, then what is the maximum no. of masses which can be placed in the same plane?

643No limitation

19. From the given data, find the balancing mass in Kg if r=0.2m required in the same plane.
Masses = 200kg, 300kg, 240 kg, 260Kg, corresponding radii = 0.2m, 0.15m, 0.25m and 0.3m.
Angles between consecutive masses = 45, 75 and 135 degrees.

14023211658

20. In case of partial balancing of locomotives, the maximum magnitude of the unbalanced force perpendicular to the line of stroke is called hammer blow and this has to be limited by proper choice of the balancing mass and its radial position.

FalseDon't KnowTrueMaybe

21. If the unbalanced system is not set right then.

Dynamic forces developRadial forces developTangential forces developStatic forces develop

22. The magnitude of swaying couple due to partial balance of the primary unbalancing force in locomotive is

inversely proportional to the distance between the centerlines of the two cylindersdirectly proportional to the distance between the centerlines of the two cylindersinversely proportional to the reciprocating massdirectly proportional to the square of the distance between the centre lines of the two cylinders

23. In the given figure, m₁=10 Kg, m₂=30Kg and m=50 Kg, if r=0.3m, l=1m, find l₂ = 0.5m, find r1 in m.

0.7561.53

24. What is not the effect of unbalanced forces?

Violation of conservation of mass principleStresses in various membersDangerous vibrationsLoad on bearings

25. In a system two masses are used to balance the unbalanced forces. Find the mass of the balancing mass which has to be situated at a distance of 20cm, if the disturbing mass is of 100 Kg having radius of rotation of 0.1m. One of the balancing mass is 30 Kg with RoR of 10cm.

20703510