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4

Centre of gravity of a thin hollow cone lies on the axis at a height of

A. One-fourth of the total height above base

B. One-third of the total height above base

C. One-half of the total height above base

D. Three-eighth of the total height above the base

Correct Answer :

B. One-third of the total height above base


Related Questions

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4

The term 'Centroid' is

A. The same as centre of gravity

B. The point of suspension

C. The point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis

D. None of the above

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4

When the lift is moving upwards with some acceleration, the pressure exerted by a man is __________ to its acceleration.

A. Directly proportional

B. Inversely proportional

C. Cube root

D. None of these

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4

A lead ball with a certain velocity is made to strike a wall, it falls down, but rubber ball of same mass and with same velocity strikes the same wall, it rebounds. Select the correct reason from the following:

A. Both the balls undergo an equal change in momentum

B. The change in momentum suffered by rubber ball is more than the lead ball

C. The change in momentum suffered by rubber ball is less than the lead ball

D. None of the above

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4

The static friction

A. Bears a constant ratio to the normal reaction between the two surfaces

B. Is independent of the area of contact, between the two surfaces

C. Always acts in a direction, opposite to that in which the body tends to move

D. All of the above

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4

The C.G. of a plane lamina will not be at its geometrical centre in the case of a

A. Right angled triangle

B. Equilateral triangle

C. Square

D. Circle

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4

In the shown figure, if the angle of inclination of the plane is increased, then acceleration of the system will

A. Increase

B. Decrease

C. Remain the same

D. None of these

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4

The velocity ratio for the third system of pulleys is

A. n

B.

C. 2n

D. 2n - 1

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4

The velocity of a body on reaching the ground from a height h, is

A. 2.√(gh)

B. √(gh)

C. √(2gh)

D. 2g.√h

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4

In ideal machines

A. Mechanical advantage is greater than velocity ratio

B. Mechanical advantage is equal to velocity ratio

C. Mechanical advantage is less than velocity ratio

D. Mechanical advantage is unity

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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

A screw jack used for lifting the loads is

A. A reversible machine

B. A non-reversible machine

C. An ideal machine

D. None of these

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4

If two bodies having masses m1 and m2 (m1>m2) have equal kinetic energies, the momentum of body having mass m1 is _________ the momentum of body having mass m2.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

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. This statement is known as

A. Newton's first law of motion

B. Newton's second law of motion

C. Newton's third law of motion

D. None of these

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4

Varingon's theorem of moments states that if a number of coplanar forces acting on a particle are in equilibrium, then

A. Their algebraic sum is zero

B. Their lines of action are at equal distances

C. The algebraic sum of their moments about any point in their plane is zero

D. The algebraic sum of their moments about any point is equal to the moment of their resultant force about the same point.

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4

The unit of energy in S.I. units is

A. Dyne

B. Watt

C. kg-m

D. Joule

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4

The product of either force of couple with the arm of the couple is called

A. Resultant couple

B. Moment of the forces

C. Resulting couple

D. Moment of the couple

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4

If a number of forces are acting at a point, their resultant will be inclined at an angle θ with the horizontal, such that

A. tanθ = ΣH/ΣV

B. tanθ = ΣV/ΣH

C. tanθ = ΣV × ΣH

D. tanθ = √(ΣV + ΣH)

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4

Forces are called concurrent when their lines of action meet in

A. One point

B. Two points

C. Plane

D. Perpendicular planes

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4

The range of projectile will be maximum for a given velocity of projectile, when the angle of projection (α) is

A. β/2

B. 30° + β/2

C. 45° + β/2

D. 60° + β/2

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4

The total energy possessed by a system of moving bodies

A. Is constant at every instant

B. Varies from point to point

C. Is maximum in the start and minimum at the end

D. Is minimum in the start and maximum at the end

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4

Which of the following is not the unit of distance?

A. Angstrom

B. Light year

C. Micron

D. Milestone

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4

Moment of inertia of a circular section about an axis perpendicular to the section is

A. πd3/16

B. πd3/32

C. πd4/32

D. πd4/64

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4

A spherical body is symmetrical about its perpendicular axis. According to Routh's rule, the moment of inertia of a body about an axis passing through its centre of gravity is (where, M = Mass of the body, and S = Sum of the squares of the two semi-axes.)

A. MS/3

B. MS/4

C. MS/5

D. None of these

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4

The time of flight (t) of a projectile on a horizontal plane is given by

A. t = 2u. sinα/g

B. t = 2u. cosα/g

C. t = 2u. tanα/g

D. t = 2u/g.sinα

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4

If n = number of members and y = number of joints, then for a perfect frame, n = ?

A. 1/2

B. 2/3

C. 3/2

D. 2/4

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4

The velocity ratio of a single purchase crab winch can be increased by

A. Increasing the length of the handle

B. Increasing the radius of the load drum

C. Increasing the number of teeth of the pinion

D. All of the above

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4

Moment of inertia of a circular section about its diameter (d) is

A. πd3/16

B. πd3/32

C. πd4/32

D. πd4/64

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4

If three forces acting in different planes can be represented by a triangle, these will be in

A. Non-equilibrium

B. Partial equilibrium

C. Full equilibrium

D. Unpredictable

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4

If a number of forces are acting at a point, their resultant is given by

A. (ΣV)2 + (ΣH)2

B. √[(ΣV)2 + (ΣH)2]

C. (ΣV)2 +(ΣH)2 +2(ΣV)(ΣH)

D. √[(ΣV)2 +(ΣH)2 +2(ΣV)(ΣH)]

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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