A sliding contact bearing is operating under stable condition. The pre...
Statement: The effective coefficient of friction between the bearing and the journal is directly proportional to the dynamic viscosity of the lubricant (μ) and the rotational speed of the journal (N).
Explanation:
To understand why option B is correct, let's break down the statement and analyze it step by step.
1. Effective coefficient of friction (f):
The effective coefficient of friction between the bearing and the journal determines the resistance to motion and the amount of friction generated. It is denoted by the symbol "f".
2. Dynamic viscosity of the lubricant (μ):
The dynamic viscosity of a lubricant measures its resistance to flow. It determines the thickness and the ability of the lubricant to form an oil film between the bearing and the journal. It is denoted by the symbol "μ".
3. Rotational speed of the journal (N):
The rotational speed of the journal is the speed at which the journal rotates in revolutions per minute (r.p.m). It determines the relative motion between the bearing and the journal.
Relationship between f, μ, and N:
Based on the given statement, the effective coefficient of friction (f) is directly proportional to both the dynamic viscosity of the lubricant (μ) and the rotational speed of the journal (N).
This means that as the dynamic viscosity of the lubricant increases or as the rotational speed of the journal increases, the effective coefficient of friction between the bearing and the journal also increases.
Implication for the bearing:
The pressure developed in the oil film (p) is influenced by the effective coefficient of friction (f). The higher the coefficient of friction, the higher the pressure developed in the oil film.
Therefore, in a sliding contact bearing operating under stable conditions, the effective coefficient of friction (f) between the bearing and the journal is directly proportional to both the dynamic viscosity of the lubricant (μ) and the rotational speed of the journal (N).
In conclusion:
Option B is correct because it accurately describes the relationship between the effective coefficient of friction (f), the dynamic viscosity of the lubricant (μ), and the rotational speed of the journal (N).
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