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51.

The principle of conservation of energy cannot be applied in case of

A.	Simple pendulum	B.	A particle moving in gravitational field
C.	Frictionless movement of a principle over a surface	D.	Frictional movement of a particle over a surface
E.	Flow of water in a pipe

52.

The resultant of a force acting on a body will be zero, if the body

A.	Rotates	B.	Does not rotate
C.	Rotates with uniform acceleration	D.	Rotates with uniform deceleration
E.	Moves along a curved path

53.

A block of weight 20 kg slides with an initial velocity of 2 m sec down an inclined plane on to a spring of stiffness 10 kg/cm. If the co--efficient of friction is 0.2, angle ? = 30 the ratio of maximum compession of spring, neglecting friction to that while considering friction would be

A.	More than one	B.	One
C.	Less than one	D.	Depends on the stiffness of spring
E.	None of the above

54.

The earth's gravitational force field is said to be conservative force field because

A.	The value of gravitational force rise is fixed	B.	The direction of gravitational force is fixed
C.	The work acted by the earth's gravitational field on a particle is independent on the path traced out by the particle	D.	The work acted by the erth's gravitational field will cause same path for all particles irrespective of their mass
E.	The gravitational field has only single directional component always acting normal to a body

55.

The tension in the wire rope supporting a lift moving with a uniform velocity

A.	Is more when the lift is moving downwards	B.	Is less when the lift is moving upwards
C.	Is more when the lift is moving upwards	D.	Is less when the lift is moving down-wards
E.	Remains constant irrespective of the lift movement

56.

A particle is of wieght 8 kg. When it is allowed to fall under the force of gravity its momentum at the time t = 2 sec would be

A.	2 kg sec	B.	8 kg sec
C.	16 kg sec	D.	32 kg sec
E.	48 kg sec

57.

A car travelling at a speed of 60 km/hour is braked and comes to rest 6 seconds after the brakes are applied. The minimum coefficient of driction between the wheels and the road would be

A.	0.107	B.	0.283
C.	0.3	D.	0.417
E.	0.5

58.

A particle moves along a rough plane inclined at 30? to the horizontal. The co-efficient of friction between the particle and the plane is 0.1. Its initial velocity is 15 m/sec. The ratio of the velocity of the particle when it move down the plane to that when it move up the plane would be in the regions

A.	2 ? 3	B.	4 ? 6
C.	5 ? 7	D.	8 ? 10
E.	10 ? 13

59.

The work done in sliding a block of weight of 50 kg up a plane inclined at an angle of 30? to the horizontal so that the block is lifted through 1 m (

A.	More than 50 kgm	B.	50 kgm
C.	Less than 5 kgm	D.	15 kgm only
E.	None of the above

60.

In which case power required would be more

A.	In lifting up a weight of 100 kg at a constant speed of 3 m/sec	B.	In lifting up a weight of 100 kg at a velocity of 3 m/sec but accelerating upwards at 0.5 m/sec
C.	In lowering the weight at a constant speed of 3 m/sec	D.	In lowering the weight at a velocity of 3 m/sec and acceleration of 1 m/sec2
E.	In lowering a weight of 100 kg along an a inclined plane at an angle of 45? with