A body, resting on a rough horizontal plane required a pull of 181 N inclined at 30° to the plane just to move it. It was recorded that a push of 220 N inclined at 30°° to the plane just moved the body. Estimate the coefficient of friction.

A body, resting on a rough horizontal plane required a pull of 181 N inclined at 30° to the plane just to move it. It was recorded that a push of 220 N inclined at 30° to the plane just moved the body. Estimate the weight of the body in N.

A

2000N

B

2500N

C

1000N

D

4000N

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)

A body of weight W is required to move up the rough inclined plane whose angle of inclination with the horizontal is α. The effort applied parallel to the plane is given by (where $$\mu $$ = $$\tan \varphi $$ = Coefficient of friction between the plane and the body)

A

$${\text{P}} = {\text{W}}\tan \alpha $$

B

$${\text{P}} = {\text{W}}\tan \left( {\alpha + \varphi } \right)$$

C

$${\text{P}} = {\text{W}}\left( {\sin \alpha + \mu \cos \alpha } \right)$$

D

$${\text{P}} = {\text{W}}\left( {\cos \alpha + \mu \sin \alpha } \right)$$

A body of weight W is required to move up the rough inclined plane whose angle of inclination with the horizontal is $$\alpha $$. The effort applied parallel to the plane is given by (where $$\mu $$ = $$\tan \varphi $$ = Coefficient of friction between the plane and the body)

A

$${\text{P}} = {\text{W}}\tan \alpha $$

B

$${\text{P}} = {\text{W}}\tan \left( {\alpha + \varphi } \right)$$

C

$${\text{P}} = {\text{W}}\left( {\sin \alpha + \mu \cos \alpha } \right)$$

D

$${\text{P}} = {\text{W}}\left( {\cos \alpha + \mu \sin \alpha } \right)$$

A body of mass 10 kg is resting on a rough horizontal surface of coefficient of friction 0.3. When 15 N force is applied horizontally on the body, then the friction force developed between the surface and the body will be: (Take g = 9.8 m/s2)

A

29.4 N

B

15 N

C

3 N

D

4.5 N

A body of weight 100 N is placed on a rough horizontal plane. What will be the co-efficient of friction between surfaces if a horizontal force of 60 N just causes the body to slide over the horizontal plane ?

A

0.3

B

0.4

C

0.5

D

0.6

A body is resting on a plane inclined at angle 30° to horizontal. What force would be required to slide it down, if the coefficient of friction between body and plane is 0.3?

A

Zero

B

1 kg

C

5 kg

D

10 kg

E

None of these

Match the column. a. Detailed estimate 1. Estimate of additional works during the process b. Supplementary estimate 2. Prepared for approx. rates initially c. Revised estimate 3. Includes details and cost of everything d. Rough estimate 4. Prepared when the costs exceed more than 5%

A

a - 2, b - 1, c - 4, d - 3

B

a - 3, b - 4, c - 1, d - 2

C

a - 3, b - 1, c - 4, d - 2

D

a - 1, b - 3, c - 4, d - 2

If a body is lying on a plane whose inclination with the horizontal is less than the angle of friction, then i. a force is required to move the body upwards ii. a force is required to move the body downward iii. the body will not be in equilibrium The correct answer is

A

only (i)

B

only (ii)

C

both (i) and (ii)

D

both (i) and (iii)

If a body is lying on a plane whose inclination with the horizontal is less than the angle of friction, then
i. a force is required to move the body upwards
ii. a force is required to move the body downward
iii. the body will not be in equilibrium
The correct answer is

A

only (i)

B

only (ii)

C

both (i) and (ii)

D

both (i) and (iii)

A body, resting on a rough horizontal plane required a pull of 181 N inclined at 30° to the plane just to move it. It was recorded that a push of 220 N inclined at 30°° to the plane just moved the body. Estimate the coefficient of friction.

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