In an oil lubricated journal bearing, the coefficient of friction between the journal and the bearing

A Remains constant at all speeds
B Is minimum at zero speed and increases monotonically with increase in speed
C Is maximum at zero speed and decreases monotonically with increase in speed
D Becomes minimum at an optimum speed and then increases with further increase in speed

Correct Answer: Becomes minimum at an optimum speed and then increases with further increase in speed

Bissoy MCQ
#Mechanical Engineering #Machine Design

Related Questions

In a boundary lubricated bearing, there is a __________ of lubricant between the journal and the bearing.
A Thick film
B Thin film
C Either A or B
D None of these
A friction circle is a circle drawn when a journal rotates in a bearing. Its radius depends upon the coefficient of friction and the
A Magnitude of the forces on journal
B Angular velocity of journal
C Clearance between journal and bearing
D Radius of journal
The radius of a friction circle for a shaft rotating inside a bearing is (where r = Radius of shaft and $$\tan \varphi $$  = Coefficient of friction between the shaft and bearing)
A $${\text{r}}\sin \varphi $$
B $${\text{r}}\cos \varphi $$
C $${\text{r}}\tan \varphi $$
D $$\frac{{\text{r}}}{2}\cos \varphi $$
A sliding bearing in which although lubricant is present, the working surfaces __________ contact each other at least part of the time, is called boundary lubricated bearing.
A Partially
B Fully
C Either A or B
D None of these
In a journal bearing, the load on the bearing is __________ to the axis of the journal.
A Parallel
B Perpendicular
C Both A and B
D None of these
In a partial journal bearing, the angle of contact of the bearing with the journal is
A 120°
B 180°
C 270°
D 360°
In a full journal bearing, the angle of contact of the bearing with the journal is
A 120°
B 180°
C 270°
D 360°
The frictional torque transmitted in a flat pivot bearing, considering uniform wear, is (where μ = Coefficient of friction, W = Load over the bearing and R = Radius of bearing surface)
A $$\frac{1}{2}$$μWR
B $$\frac{2}{3}$$μWR
C $$\frac{3}{4}$$μWR
D μWR
After the increase of price of oil by 40%, a family decided to reduce its oil consumption so that the expenditure for oil goes up by 26% only. If the total consumption of oil before the price rise was 10 kg per month, then what is the current consumption of oil per month (in kg)?
A 8
B 8.50
C 9
D None of these
If p = bearing pressure on projected bearing area, Z = absolute viscosity of lubricant and N = speed of journal, then the bearing characteristic number is given by
A $$\frac{{{\text{ZN}}}}{{\text{p}}}$$
B $$\frac{{\text{p}}}{{{\text{ZN}}}}$$
C $$\frac{{\text{Z}}}{{{\text{pN}}}}$$
D $$\frac{{\text{N}}}{{{\text{Zp}}}}$$

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