A body of weight ‘w’ placed on an inclined plane is acted upon by a force ‘P’ parallel to the plane which causes the body just to move up the plane. If the angle of inclination of the plane is ‘θ’ and angle of friction is ‘φ’, the minimum value of ‘P’, is

A body of weight w placed on an inclined plane is acted upon by a force P parallel to the plane which causes the body just to move up the plane. If the angle of inclination of the plane is $$\theta $$ and angle of friction is $$\varphi $$, the minimum value of P, is

A

$$\frac{{{\text{w}}\sin \left( {\varphi - \theta } \right)}}{{\cos \varphi }}$$

B

$$\frac{{{\text{w}}\sin \left( {\theta - \varphi } \right)}}{{\cos \varphi }}$$

C

$$\frac{{{\text{w}}\cos \left( {\theta + \varphi } \right)}}{{\cos \varphi }}$$

D

$$\frac{{{\text{w}}\sin \theta \cos\left( {\theta - \varphi } \right)}}{{\sin\varphi }}$$

Which of the following is NOT true about Frictional force? A. Friction is the force which opposes the relative motion of two surfaces in contact. B. The force of friction that acts when a body is moving (sliding) on a surface is called sliding friction. C. Friction in machines wastes energy and also causes wear and tear. D. Rolling friction is much more than sliding friction, the use of ball bearings in a machine considerably reduces friction.

A

D

B

A

C

D

B

What is the condition for a tree to be weight balanced. where a is factor and n is a node? >= a*weight and weight >= a*weight. b) weight >= a*weight and weight >= a*weight. c) weight >= a*weight and weight >= a*weight. d) weight is a non zero

A

weight >= a*weight and weight >= a*weight.

B

n.left

C

n.left

D

n.left

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, 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

When a body resting on an inclined surface just begins to slide down the inclined plane under the action of its own weight, then the angle of inclination of the inclined plane is

A

Greater than the angle of repose

B

Less than the angle of repose

C

Equal to the angle of repose

D

Vertical

E

Horizontal

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

0.17

B

0.2

C

0.5

D

0.75

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 of weight ‘w’ placed on an inclined plane is acted upon by a force ‘P’ parallel to the plane which causes the body just to move up the plane. If the angle of inclination of the plane is ‘θ’ and angle of friction is ‘φ’, the minimum value of ‘P’, is

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