Related Questions

For a shoe brake, the equivalent coefficient of friction is equal to (where $$\mu $$ = Actual coefficient of friction and $$\theta $$ = Semi-block angle)
A $$\frac{{2\mu \sin \theta }}{{\theta + \sin \theta }}$$
B $$\frac{{\mu \sin \theta }}{{2\theta + \sin 2\theta }}$$
C $$\frac{{4\mu \sin \theta }}{{\theta + \sin \theta }}$$
D $$\frac{{4\mu \sin \theta }}{{2\theta + \sin 2\theta }}$$
A semicircular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi circular disc and horizontal surface is µ. This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will
A Remain horizontal
B Slant up towards direction of pull
C Slant down towards direction of pull
D None of the above
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 $$\frac{{\text{r}}}{2}\cos \varphi $$
The particular places where pedestrians are to cross the pavement are properly marked by the pavement marking known as
A stop lines
B turn markings
C crosswalk lines
D lane lines
The attainment of super elevation by rotation of pavement about the inner edge of the pavement
A is preferable in steep terrain
B results in balancing the earthwork
C avoids the drainage problem in flat terrain
D does not change the vertical alignment of road
The number of repetitions, which the pavement thickness designed for a given wheel load should be able to support during the life of pavement is
A 1000
B 10000
C 100000
D 1000000
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
The dynamic friction is the friction experienced by a body, when the body
A is in motion
B is at rest
C just begins to slide over the surface of the other body
D none of the mentioned
Coulomb friction is the friction between
A Bodies having relative motion
B Two dry surfaces
C Two lubricated surfaces
D Solids and liquids

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