Related Questions

The ratio of limiting friction and normal reaction is known as
A Coefficient of friction
B Angle of friction
C Angle of repose
D Sliding friction
The skidding away of the vehicle on a level circular path can be avoided if the force of friction between the wheels and the ground is __________ the centrifugal force.
A Less than
B Greater than
C Equal to
D None of these
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
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
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
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 $$\frac{{4\mu \sin \theta }}{{2\theta + \sin 2\theta }}$$
Dynamic friction as compared to static friction is
A Same
B More
C Less
D May be less of more depending on nature of surfaces and velocity
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 ratio of static friction to dynamic friction is always
A Equal to one
B Less than one
C Greater than one
D None of these

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