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A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed is
- a)5367 r.p.m.
- b)6000 r.p.m.
- c)9360 r.p.m.
- d)2000 r.p.m.
Correct answer is option 'A'. Can you explain this answer?
Most Upvoted Answer
A shaft has two heavy rotors mounted on it. The transverse natural fre...
Calculation of Lowest Critical Speed of Shaft with Two Rotors
Given data:
Transverse natural frequency of first rotor (f1) = 100 Hz
Transverse natural frequency of second rotor (f2) = 200 Hz
Step 1: Calculation of Critical Speed of Each Rotor
- Critical speed of the rotor is the speed at which the frequency of rotation coincides with the natural frequency of the rotor.
- The critical speed of each rotor can be calculated using the formula:
Critical speed (Nc) = (f * 60) / p
Where,
f = natural frequency of the rotor
p = number of poles of the motor
For the first rotor:
Nc1 = (100 * 60) / 2 = 3000 rpm
For the second rotor:
Nc2 = (200 * 60) / 2 = 6000 rpm
Step 2: Calculation of Lowest Critical Speed of Shaft
- The lowest critical speed of the shaft is the speed at which the natural frequencies of both rotors coincide.
- The natural frequencies of the rotors are in the ratio of 1:2, which means that at some speed, their frequencies will become equal.
- Let the lowest critical speed of the shaft be Nc.
Then, (f2 / f1) = (Nc / Nc1)^2
(Nc / Nc1)^2 = 2
Nc / Nc1 = √2
Nc = Nc1 * √2
Nc = 3000 * √2 = 5367 rpm (approx.)
Therefore, the lowest critical speed of the shaft with two rotors mounted on it is 5367 rpm. The correct answer is option (a).
Given data:
Transverse natural frequency of first rotor (f1) = 100 Hz
Transverse natural frequency of second rotor (f2) = 200 Hz
Step 1: Calculation of Critical Speed of Each Rotor
- Critical speed of the rotor is the speed at which the frequency of rotation coincides with the natural frequency of the rotor.
- The critical speed of each rotor can be calculated using the formula:
Critical speed (Nc) = (f * 60) / p
Where,
f = natural frequency of the rotor
p = number of poles of the motor
For the first rotor:
Nc1 = (100 * 60) / 2 = 3000 rpm
For the second rotor:
Nc2 = (200 * 60) / 2 = 6000 rpm
Step 2: Calculation of Lowest Critical Speed of Shaft
- The lowest critical speed of the shaft is the speed at which the natural frequencies of both rotors coincide.
- The natural frequencies of the rotors are in the ratio of 1:2, which means that at some speed, their frequencies will become equal.
- Let the lowest critical speed of the shaft be Nc.
Then, (f2 / f1) = (Nc / Nc1)^2
(Nc / Nc1)^2 = 2
Nc / Nc1 = √2
Nc = Nc1 * √2
Nc = 3000 * √2 = 5367 rpm (approx.)
Therefore, the lowest critical speed of the shaft with two rotors mounted on it is 5367 rpm. The correct answer is option (a).
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Community Answer
A shaft has two heavy rotors mounted on it. The transverse natural fre...
1/f^�=1/f�^�+1/f�^�
f=89.44Hz
Critical speed =5366.4rpm
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Question Description
A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed isa)5367 r.p.m.b)6000 r.p.m.c)9360 r.p.m.d)2000 r.p.m.Correct answer is option 'A'. Can you explain this answer? for Mechanical Engineering 2025 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed isa)5367 r.p.m.b)6000 r.p.m.c)9360 r.p.m.d)2000 r.p.m.Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed isa)5367 r.p.m.b)6000 r.p.m.c)9360 r.p.m.d)2000 r.p.m.Correct answer is option 'A'. Can you explain this answer?.
A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed isa)5367 r.p.m.b)6000 r.p.m.c)9360 r.p.m.d)2000 r.p.m.Correct answer is option 'A'. Can you explain this answer? for Mechanical Engineering 2025 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed isa)5367 r.p.m.b)6000 r.p.m.c)9360 r.p.m.d)2000 r.p.m.Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed isa)5367 r.p.m.b)6000 r.p.m.c)9360 r.p.m.d)2000 r.p.m.Correct answer is option 'A'. Can you explain this answer?.
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A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed isa)5367 r.p.m.b)6000 r.p.m.c)9360 r.p.m.d)2000 r.p.m.Correct answer is option 'A'. Can you explain this answer?, a detailed solution for A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed isa)5367 r.p.m.b)6000 r.p.m.c)9360 r.p.m.d)2000 r.p.m.Correct answer is option 'A'. Can you explain this answer? has been provided alongside types of A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed isa)5367 r.p.m.b)6000 r.p.m.c)9360 r.p.m.d)2000 r.p.m.Correct answer is option 'A'. Can you explain this answer? theory, EduRev gives you an
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