Coefficient of friction depends on

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

$$\frac{{4\mu \sin \theta }}{{2\theta + \sin 2\theta }}$$

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 coefficient of friction depends upon

A

Nature of surfaces

B

Area of contact

C

Shape of the surfaces

D

All of the above

The coefficient of friction between the belt and pulley depends upon the

A

Material of belt and pulley

B

Slip of belt

C

Speed of belt

D

All of these

Coefficient of friction depends upon

A

Area of contact only

B

Nature of surface only

C

Both (A) and (B)

D

None of these

The coefficient of friction depends on

A

Area of contact

B

Shape of surfaces

C

Strength of surfaces

D

Nature of surface

The coefficient of friction in belt drive depends upon

A

Material of belt

B

Material of pulley

C

Materials of belt and pulley

D

Belt velocity

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

Coefficient of friction depends on

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