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A 70 kg man stands in contact against the inner wall of a hollow cylindrical drum of radius 3 m rotating about its vertical axis with 200 rev/min. The coefficient of friction between the wall and his clothing is 0.15. When the floor is suddenly removed, what is the minimum rotational speed o f the cylinder to enable the man to remain stuck to the wall with out falling (approximately)?
  • a)
    5 rad/s
  • b)
    10 rad/s
  • c)
    15 rad/s
  • d)
    20 rad/s
Correct answer is option 'A'. Can you explain this answer?
Most Upvoted Answer
A 70 kg man stands in contact against the inner wall of a hollow cylin...
Given parameters:
- Mass of man, m = 70 kg
- Radius of drum, r = 3 m
- Rotational speed of drum, ω = 200 rev/min = 20π rad/s
- Coefficient of friction between wall and clothing, μ = 0.15

To calculate:
- Minimum rotational speed of drum to enable man to remain stuck to wall without falling

Assumptions:
- The man remains in contact with the wall throughout the motion
- Friction is the only force acting on the man

Solution:
1. Calculate the gravitational force on the man:
- Gravitational acceleration, g = 9.8 m/s²
- Gravitational force, Fg = mg = 70 kg × 9.8 m/s² = 686 N

2. Calculate the maximum frictional force between the wall and the man:
- Maximum frictional force, Ff = μN
- Normal force, N = Fg (since the man is in contact with the wall)
- Maximum frictional force, Ff = μFg = 0.15 × 686 N = 103 N

3. Calculate the minimum required centripetal force on the man to keep him stuck to the wall:
- Centripetal force, Fc = mrω²
- Minimum required centripetal force, Fc,min = Ff (since friction is the only force acting on the man)
- Fc,min = mrω² = 70 kg × (3 m) × ω²
- ω² = Fc,min / (mr) = Ff / (mr) = 103 N / (70 kg × 3 m) = 1.55 m/s²

4. Calculate the minimum rotational speed required for the man to remain stuck to the wall:
- ω = √(Fc,min / (mr)) = √(1.55 m/s²) = 1.25 rad/s

5. Convert the answer to revolutions per minute (rpm):
- Minimum rotational speed, ω = 1.25 rad/s
- Minimum rotational speed, ω = 1.25 × (60 / 2π) rpm = 11.92 rpm ≈ 12 rpm

Answer:
The minimum rotational speed of the drum to enable the man to remain stuck to the wall without falling is approximately 12 rpm, which is closest to option A (5 rad/s) among the given options.
Free Test
Community Answer
A 70 kg man stands in contact against the inner wall of a hollow cylin...
Given:
- Mass of the man (m) = 70 kg
- Radius of the cylindrical drum (r) = 3 m
- Rotational speed of the drum (ω) = 200 rev/min
- Coefficient of friction between the wall and the man's clothing (μ) = 0.15

To find:
- Minimum rotational speed of the cylinder to enable the man to remain stuck to the wall without falling

Solution:

1. Determine the gravitational force on the man:
- Gravitational force (Fg) = mg = 70 kg x 9.8 m/s² = 686 N

2. Determine the centrifugal force on the man:
- Centrifugal force (Fc) = mrω² = 70 kg x (3 m) x (200 rev/min x 2π/60 s)² = 6591.8 N

3. Determine the force of friction between the man's clothing and the wall:
- Force of friction (Ff) = μN, where N is the normal force on the man
- At the minimum rotational speed, the force of friction is equal and opposite to the gravitational force: Ff = Fg
- Therefore, μN = mg
- N = mg/μ = 686 N / 0.15 = 4573.3 N
- Ff = μN = 0.15 x 4573.3 N = 686 N

4. Determine the net force on the man:
- Net force (Fnet) = Fc - Ff
- At the minimum rotational speed, the net force is zero: Fnet = 0
- Therefore, Fc = Ff
- mrω² = μN
- ω² = μN/mr = 0.15 x 4573.3 N / (70 kg x 3 m) = 3.69 rad/s²
- ω = √(3.69) = 1.92 rad/s

5. Convert the answer to RPM:
- ω = 1.92 rad/s x 60 s/2π = 18.3 rev/min

6. Round the answer to the nearest option:
- The minimum rotational speed is approximately 5 rad/s (Option A).

Therefore, the correct answer is option 'A' (5 rad/s).
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A 70 kg man stands in contact against the inner wall of a hollow cylindrical drum of radius 3 m rotating about its vertical axis with 200 rev/min. The coefficient of friction between the wall and his clothing is 0.15. When the floor is suddenly removed, what is the minimum rotational speed o f the cylinder to enable the man to remain stuck to the wall with out falling (approximately)?a)5 rad/sb)10 rad/sc)15 rad/sd)20 rad/sCorrect answer is option 'A'. Can you explain this answer?
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A 70 kg man stands in contact against the inner wall of a hollow cylindrical drum of radius 3 m rotating about its vertical axis with 200 rev/min. The coefficient of friction between the wall and his clothing is 0.15. When the floor is suddenly removed, what is the minimum rotational speed o f the cylinder to enable the man to remain stuck to the wall with out falling (approximately)?a)5 rad/sb)10 rad/sc)15 rad/sd)20 rad/sCorrect answer is option 'A'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about A 70 kg man stands in contact against the inner wall of a hollow cylindrical drum of radius 3 m rotating about its vertical axis with 200 rev/min. The coefficient of friction between the wall and his clothing is 0.15. When the floor is suddenly removed, what is the minimum rotational speed o f the cylinder to enable the man to remain stuck to the wall with out falling (approximately)?a)5 rad/sb)10 rad/sc)15 rad/sd)20 rad/sCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A 70 kg man stands in contact against the inner wall of a hollow cylindrical drum of radius 3 m rotating about its vertical axis with 200 rev/min. The coefficient of friction between the wall and his clothing is 0.15. When the floor is suddenly removed, what is the minimum rotational speed o f the cylinder to enable the man to remain stuck to the wall with out falling (approximately)?a)5 rad/sb)10 rad/sc)15 rad/sd)20 rad/sCorrect answer is option 'A'. Can you explain this answer?.
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