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4

A shell of mass 100 kg travelling with a velocity of 10 m/sec breaks into two equal pieces during an explosion which provides an extra kinetic energy of 20000 Joules. If the pieces continue to move in the same direction as before, then the speed of the faster one must be

A. 20 m/sec

B. 30 m/sec

C. 40 m/sec

D. 50 m/sec

Correct Answer :

B. 30 m/sec


Related Questions

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4

A ball moving on a smooth horizontal table hits a rough vertical wall, the coefficient of restitution between ball and wall being 1/3. The ball rebounds at the same angle. The fraction of its kinetic energy lost is

A. 1/3

B. 2/3

C. 1/9

D. 8/9

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4

Time of flight of a projectile on a horizontal plane, is

A. 2u sinα/g

B. 2u cosα/g

C. 2u tanα/g

D. 2u cotα/g

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4

For a given velocity of a projectile, the range is maximum when the angle of projection is

A. 30°

B. 45°

C. 90°

D.

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4

Two loads of 50 kg and 75 kg are hung at the ends of a rope passing over a smooth pulley shown in below figure. The tension in the string is:

A. 50 kg

B. 75 kg

C. 25 kg

D. 60 kg

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4

The practical units of work, is

A. Erg

B. Joule

C. Newton

D. Dyne

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4

Varingons theorem of moments states

A. Arithmetical sum of the moments of two forces about any point, is equal to the moments of their resultant about that point

B. Algebraic sum of the moments of two forces about any point, is equal to the moment of their resultant about that point

C. Arithmetical sum of the moments of the forces about any point in their plane, is equal to the moment of their resultant about that point

D. Algebraic sum of the moments of the forces about any point in their plane, is equal to the moment of their resultant about that point

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4

Three forces which act on a rigid body to keep it in equilibrium. The forces must be coplanar and

A. Concurrent

B. Parallel

C. Concurrent parallel

D. None of these

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4

The height at which the end of a rope of length l should be tied so that a man pulling at the other end may have the greatest tendency to overturn the pillar, is

A. ¾ l

B. ½ l

C. l/√2

D. 2/√3 l

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4

The torque produced by a force depends on (i) The magnitude of the force (ii) The direction of the force (iii) The point of application of the force relative to origin The correct answer is

A. Only (i)

B. Both (i) and (ii)

C. Both (i) and (iii)

D. All (i), (ii) and (iii)

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4

If a set of given forces are such that their free vectors build a closed polygon, then

A. The resultant force and resultant couple are always zero

B. The resultant force is zero but resultant couple is not zero

C. The resultant force is zero but resultant couple may not be zero

D. The resultant force and resultant couple both may not be zero

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4

Two balls of masses 3 kg and 6 kg are moving with velocities of 4 m/sec and 1 m/sec respectively, towards each other along the line of their centers. After impact the 3 kg ball comes to rest. This can happen only if the coefficient of restitution between the balls is

A. 2/3

B. 1/5

C. 3/5

D. 1/3

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4

The force polygon representing a set of forces in equilibrium is a

A. Triangle

B. Open polygon

C. Closed polygon

D. Parallelogram

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4

The condition of equilibrium for any system of forces in a plane is

A. That polygon of forces must close

B. That resultant couple must be zero

C. Both (A) and (B)

D. None of the above

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4

The beam shown in below figure is supported by a hinge at A and a roller at B. The reaction RA of the hinged support A of the beam, is

A. 10.8 t

B. 10.6 t

C. 10.4 t

D. 10.2 t

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4

If two forces are in equilibrium, then the forces must (i) Be equal in magnitude (ii) Be opposite in sense (iii) Act along the same line The correct answer is

A. (i) and (ii)

B. (i) and (iii)

C. Only (i)

D. All (i), (ii) and (iii)

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4

The necessary condition of equilibrium of a body is:

A. Algebraic sum of horizontal components of all the forces must be zero

B. Algebraic sum of vertical components of all the forces must be zero

C. Algebraic sum of the moments of the forces about a point must be zero

D. All (a), (b) and (c)

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4

A cable loaded with 0.5 tonne per horizontal metre span is stretched between supports in the same horizontal line 400 m apart. If central dip is 20 m, the minimum tension in the cable, will be

A. 200 tonnes at the centre

B. 500 tonnes at the centre

C. 200 tonnes at the right support

D. 200 tonnes at the left support

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4

If two forces each equal to T in magnitude act at right angles, their effect may be neutralised by a third force acting along their bisector in opposite direction whose magnitude will be

A. 2 T

B. 1/2 T

C. √2 T

D. 3 T

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4

A load of 500 kg was lifted through a distance of 13 cm. by an effort of 25 kg which moved through a distance of 650 cm. The efficiency of the lifting machine is

A. 50 %

B. 40 %

C. 55 %

D. 30 %

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4

If the resultant of two forces has the same magnitude as either of the force, then the angle between the two forces is

A. 30°

B. 45°

C. 60°

D. 120°

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4

The potential energy of a particle falling through a straight shaft drilled through the earth (assumed homogenous and spherical) is proportional to

A. log r

B. r

C.

D. 1/r Where r is the distance of the particle from centre of the earth

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4

The reaction at the support B of the beam shown in below figure is

A. 1.6 t

B. 9.6 t

C. 8.5 t

D. 0.5 t

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4

P is the force acting on a body whose mass is m and acceleration is f. The equation P - mf= 0, is known as

A. Equation of dynamics

B. Equation of dynamic equilibrium

C. Equation of statics

D. None of these

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4

The piston of a steam engine moves with a simple harmonic motion. The crank rotates 120 r.p.m. and the stroke length is 2 metres. The linear velocity of the piston when it is at a distance of 0.5 metre from the centre, is

A. 5.88 m/sec

B. 8.88 m/sec

C. 10.88 m/sec

D. 12.88 m/sec

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4

The ends of a string weighing w/metre are attached to two points at the same horizontal level. If the central dip is very small, the horizontal tension of the string throughout is

A. wl/4d

B. wl²/4d

C. wl²/8d

D. wl²/16d

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4

The shape of a suspended cable for a uniformly distributed load over it is

A. Circular

B. Parabolic

C. Catenary

D. Cubic parabola

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4

One end of a light string 4 m in length is fixed to a point on a smooth wall and the other end fastened to a point on the surface of a smooth sphere of diameter 2.25 m and of weight 100 kg. The reaction between the sphere and the wall of the arrangement made is

A. 102.5 kg

B. 105.5 kg

C. 108.5 kg

D. 110 kg

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4

The equation of motion of a particle starting from rest along a straight line is x = t3 - 3t2+ 5. The ratio of the accelerations after 5 sec and 3 sec will be

A. 2

B. 3

C. 4

D. 5

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4

The velocity of a moving body, is

A. A vector quantity

B. A scalar quantity

C. A scalar as well as a vector quantity

D. None of these

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4

The masses of two balls are in the ratio of 2 : 1 and their respective velocities are in the ratio of 1 : 2 but in opposite direction before impact. If the coefficient of restitution is ½, the velocities of separation of the balls will be equal to

A. Original velocity in the same direction

B. Half the original velocity in the same direction

C. Half the original velocity in the opposite direction

D. Original velocity in the opposite direction