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 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 body of weight 'W' is required to move up on rough inclined plane whose angle of inclination with the horizontal is 'α'. The effort applied parallel to the plane is given by (where μ = tanφ = Coefficient of friction between the plane and the body.)
A P = W tanα
B P = W tan (α + φ)
C P = W (sinα + μcosα)
D P = W (cosα + μsinα)
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
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 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
Static friction is always __________ dynamic friction.
A Equal to
B Less than
C Greater than
D None of these
Friction produced by the formation of wakes is called the __________ friction.
A Disk
B Skin
C Form
D None of these

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