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What is the correct answer?

4

The velocity ratio for the first system of pulleys is (where n is the number of pulleys.)

A. n

B.

C. 2n

D. 2n - 1

Correct Answer :

C. 2n


Related Questions

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4

According to Newton's first law of motion,

A. Everybody continues in its state of rest or of uniform motion, in a straight line, unless it is acted upon by some external force

B. The rate of change of momentum is directly proportional to the impressed force, and takes place in the same direction, in which the force acts

C. To every action, there is always an equal and opposite reaction

D. None of the above

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4

A ladder is resting on a smooth ground and leaning against a rough vertical wall. The force of friction will act

A. Towards the wall at its upper end

B. Away from the wall at its upper end

C. Downward at its upper end

D. Upward at its upper end

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4

The periodic time (T) is given by (where, ω = Angular velocity of particle in rad/s.)

A. ω/2π

B. 2π/ω

C. 2π × ω

D. π/ω

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4

Which one of the following statements is not correct?

A. The tangent of the angle of friction is equal to coefficient of friction

B. The angle of repose is equal to angle of friction

C. The tangent of the angle of repose is equal to coefficient of friction

D. The sine of the angle of repose is equal to coefficient to friction

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4

Which of the following is not the unit of energy?

A. kg m

B. kcal

C. Watt

D. Watt hours

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4

A block of mass m1, placed on an inclined smooth plane is connected by a light string passing over a smooth pulley to mass m2, which moves vertically downwards as shown in the below figure. The tension in the string is

A. m1/m2

B. m1. g. sin α

C. m1.m2/m1 + m2

D. m1. m2.g (1 + sin α)/(m1 + m2)

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4

According to principle of moments

A. If a system of coplanar forces is in equilibrium, then their algebraic sum is zero

B. If a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero

C. The algebraic sum of the moments of any two forces about any point is equal to moment of the resultant about the same point

D. Positive and negative couples can be balanced

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4

In order to completely specify angular displacement by a vector, it must fix

A. Direction of the axis of rotation

B. Magnitude of angular displacement

C. Sense of angular displacement

D. All of these

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4

One end of a helical spring is fixed while the other end carries the load W which moves with simple harmonic motion. The frequency of motion is given by (where δ = Deflection of the spring.)

A. 2π. √(g/δ)

B. 1/2π. √(g/δ)

C. 2π. √(δ/g)

D. 1/2π. √(δ/g)

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4

If the masses of both the bodies, as shown in the below figure, are reduced to 50 percent, then tension in the string will be

A. Same

B. Half

C. Double

D. None of these

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4

Kinetic friction is the

A. Tangent of angle between normal reaction and the resultant of normal reaction and the limiting friction

B. Ratio of limiting friction and normal reaction

C. The friction force acting when the body is just about to move

D. The friction force acting when the body is in motion

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4

The velocity ratio of a first system of pulleys with 4 pulleys is

A. 4

B. 8

C. 16

D. 20

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4

The moment of inertia of a solid cone of mass m and base radius r about its vertical axis is

A. 3mr2/5

B. 3mr2/10

C. 2mr2/5

D. 4mr2/5

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4

A smooth cylinder lying on a __________ is in neutral equilibrium.

A. Curved surface

B. Convex surface

C. Horizontal surface

D. None of these

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4

The units of moment of inertia of an area are

A. kg-m²

B. m⁴

C. kg/m²

D.

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4

Tension in the cable supporting a lift is more when the lift is moving __________ with an acceleration.

A. Upwards

B. Downwards

C. Horizontal

D. None of these

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4

The velocity of a particle moving with simple harmonic motion is __________ at the mean position.

A. Zero

B. Minimum

C. Maximum

D. None of these

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4

A trolley wire weighs 1.2 kg per meter length. The ends of the wire are attached to two poles 20 meters apart. If the horizontal tension is 1500 kg find the dip in the middle of the span

A. 2.5 cm

B. 3.0 cm

C. 4.0 cm

D. 5.0 cm

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4

The weight of a body is due to

A. Gravitational pull exerted by the earth

B. Forces experienced by body in atmosphere

C. Force of attraction experienced by particles

D. Gravitational force of attraction towards the centre of the earth

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4

Moment of inertia of a hollow circular section, as shown in the below figure about an axis perpendicular to the section, is __________ than that about X-X axis.

A. Two times

B. Same

C. Half

D. None of these

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4

Which of the following are vector quantities?

A. Linear displacement

B. Linear velocity

C. Linear acceleration

D. All of these

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4

The resultant of two equal forces P making an angle θ, is given by

A. 2P sinθ/2

B. 2P cosθ/2

C. 2P tanθ/2

D. 2P cotθ/2

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4

A single force and a couple acting in the same plane upon a rigid body

A. Balance each other

B. Cannot balance each other

C. Produce moment of a couple

D. Are equivalent

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4

The force induced in the string BC due to the load W as shown in the below figure is

A. W sinθ

B. W cosθ

C. W tanθ

D. W cotθ

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4

If the body falls freely under gravity, then the gravitational acceleration is taken as

A. +8.9 m/s2

B. -8.9 m/s2

C. +9.8 m/s2

D. -9.8 m/s2

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4

The unit of angular velocity is

A. m/min

B. rad/s

C. Revolutions/min

D. Both (B) and (C)

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4

Three forces acting on a rigid body are represented in magnitude, direction and line of action by the three sides of a triangle taken in order. The forces are equivalent to a couple whose moment is equal to

A. Area of the triangle

B. Twice the area of the triangle

C. Half the area of the triangle

D. None of these

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4

The moment of inertia of a square of side a about its diagonal is

A. a2/8

B. a3/12

C. a4/12

D. a4/16

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4

The time of flight (t) of a projectile on an upward inclined plane is (where u = Velocity of projection, α = Angle of projection, and β = Inclination of the plane with the horizontal.)

A. t = g cos β/2u sin (α - β)

B. t = 2u sin (α - β)/g cos β

C. t = g cos β/2u sin (α + β)

D. t = 2u sin (α + β)/g cos β

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4

The resultant of the two forces P and Q is R. If Q is doubled, the new resultant is perpendicular to P. Then

A. P = Q

B. Q = R

C. Q = 2R

D. None of these