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4

The total momentum of a system of masses (i. e. moving bodies) in any one direction remains constant, unless acted upon by an external force in that direction. This statement is called

A. Newton's first law of motion

B. Newton's second law of motion

C. Principle of conservation of energy

D. Principle of conservation of momentum

Correct Answer :

D. Principle of conservation of momentum


Related Questions

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4

A flywheel on a motor goes from rest to 1000 rpm in 6 sec. The number of revolutions made is nearly equal to

A. 25

B. 50

C. 100

D. 250

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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

The coefficient of restitution for inelastic bodies is

A. Zero

B. One

C. Between zero and one

D. More than one

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4

Which of the following statement is correct?

A. The periodic time of a particle moving with simple harmonic motion is the time taken by a particle for one complete oscillation.

B. The periodic time of a particle moving with simple harmonic motion is directly proportional to its angular velocity.

C. The velocity of the particle moving with simple harmonic motion is zero at the mean position.

D. The acceleration of the particle moving with simple harmonic motion is maximum at the mean position.

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4

The law of the machine is (where P = Effort applied to lift the load, m = A constant which is equal to the slope of the line, W = Load lifted, and C = Another constant which represents the machine friction.)

A. P = mW - C

B. P = m/W + C

C. P = mW + C

D. P = C - mW

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4

Two non-collinear parallel equal forces acting in opposite direction

A. Balance each other

B. Constitute a moment

C. Constitute a couple

D. Constitute a moment of couple

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4

The velocity ratio of a differential wheel and axle with D as the diameter of effort wheel and d1 and d2 as the diameters of larger and smaller axles respectively, is

A. D/(d₁ + d₂)

B. D/(d₁ - d₂)

C. 2D/(d₁ + d₂)

D. 2D/(d₁ - d₂)

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4

The C.G. of a solid hemisphere lies on the central radius 3r

A. At distance from the plane base 3r

B. At distance from the plane base 3r

C. At distance from the plane base 3r

D. At distance from the plane base

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4

The skidding away of the vehicle on a level circular path can be avoided if the force of friction between the wheels and the ground is __________ the centrifugal force.

A. Less than

B. Greater than

C. Equal to

D. None of these

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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

Two forces are acting at an angle of 120°. The bigger force is 40 N and the resultant is perpendicular to the smaller one. The smaller force is

A. 20 N

B. 40 N

C. 120 N

D. None of these

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4

The potential energy of a vertically raised body is __________ the kinetic energy of a vertically falling body.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

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

A. W sinθ

B. W cosθ

C. W secθ

D. W cosecθ

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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

The linear velocity of a body rotating at ω rad/s along a circular path of radius r is given by

A. ω/r

B. ω.r

C. ω2/r

D. ω2.r

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4

Two like parallel forces are acting at a distance of 24 mm apart and their resultant is 20 N. It the line of action of the resultant is 6 mm from any given force, the two forces are

A. 15 N and 5 N

B. 20 N and 5 N

C. 15 N and 15 N

D. None of these

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4

The periodic time of one oscillation for a simple pendulum is (where l = Length of the pendulum.)

A. (1/2π). √(l/g)

B. (1/2π). √(g/l)

C. 2π. √(l/g)

D. None of these

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4

The principle of transmissibility of forces states that, when a force acts upon a body, its effect is

A. Same at every point on its line of action

B. Different at different points on its line of action

C. Minimum, if it acts at the centre of gravity of the body

D. Maximum, if it acts at the centre of gravity of the body

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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

A heavy ladder resting on floor and against a vertical wall may not be in equilibrium, if

A. The floor is smooth, the wall is rough

B. The floor is rough, the wall is smooth

C. The floor and wall both are smooth surfaces

D. The floor and wall both are rough surfaces

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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

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4

The acceleration of a particle moving with simple harmonic motion, at any instant is given by

A. ω.y

B. ω2.y

C. ω2/y

D. ω3.y

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4

Coplanar non-concurrent forces are those forces which __________ at one point, but their lines of action lie on the same plane.

A. Meet

B. Do not meet

C. Either A or B

D. None of these

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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

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4

The moment of inertia of a sphere of mass m and radius r, about an axis tangential to it, is

A. 2mr2/3

B. 2mr2/5

C. 7mr2/3

D. 7mr2/5

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4

The overturning of a vehicle on a level circular path can be avoided if the velocity of vehicle is __________ √(gra/h)

A. Less than

B. Greater than

C. Equal to

D. None of these

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4

According to the law of moments, 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 ideal angle of banking provided on the curves on roads depends upon

A. Weight of the vehicle

B. (Velocity)2 of the vehicle

C. Nature of the road surface

D. Coefficient of friction between the road and vehicle contact point

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4

For a self locking machine, the efficiency must be

A. Equal to 50 %

B. Less than 50 %

C. Greater than 50 %

D. 100 %

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4

The coefficient of friction depends on

A. Area of contact

B. Shape of surfaces

C. Strength of surfaces

D. Nature of surface