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4

A particle moves along a straight line such that distance (x) traversed in t seconds is given by x = t² (t - 4), the acceleration of the particle will be given by the equation

A. 6t² - 8t

B. 3t² + 2t

C. 6f - 8

D. 6f - 4

Correct Answer :

C. 6f - 8


Related Questions

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4

If a suspended body is struck at the centre of percussion, then the pressure on die axis passing through the point of suspension will be

A. Maximum

B. Minimum

C. Zero

D. Infinity

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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

Dynamic friction as compared to static friction is

A. Same

B. More

C. Less

D. May be less of more depending on nature of surfaces and velocity

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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

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

Coefficient of friction is the

A. 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

A body will begin to move down an inclined plane if the angle of inclination of the plane is _________ the angle of friction.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

A framed structure is perfect if it contains members equal to

A. 2n³

B. 2n

C.

D. 3n² Where n = number of joints in a frame

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4

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

A. Downward at its upper end

B. Upward at its upper end

C. Zero at its upper end

D. Perpendicular to the wall at its upper end

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4

A sample of metal weighs 219 gms in air, 180 gms in water, 120 gms in an unknown fluid. Then which is correct statement about density of metal

A. Density of metal can't be determined

B. Metal is twice as dense as water

C. Metal will float in water

D. Metal is twice as dense as unknown fluid

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4

The velocity ratio in case of an inclined plane inclined at angle θ to the horizontal and weight being pulled up the inclined plane by vertical effort is

A. sinθ

B. cosθ

C. tanθ

D. cosecθ

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4

When the spring of a watch is wound, it will possess

A. Strain energy

B. Kinetic energy

C. Heat energy

D. Electrical energy

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4

In the equation of virtual work, following force is neglected

A. Reaction of any smooth surface with which the body is in contact

B. Reaction of a rough surface of a body which rolls on it without slipping

C. Reaction at a point or an axis, fixed in space, around which a body is constrained to turn

D. All of the above

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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

In ideal machines, mechanical advantage is __________ velocity ratio.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

The centre of percussion of the homogeneous rod of length L suspended at the top will be

A. L/2

B. L/3

C. 3L/4

D. 2L/3

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4

The maximum frictional force which comes into play when a body just begins to slide over another surface is called

A. Limiting friction

B. Sliding friction

C. Rolling friction

D. Kinematic friction

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4

In the shown figure, the tension (T) in the string will be

A. m₁. m₂. g/(m₁ + m₂)

B. 2m₁. m₂. g/(m₁ + m₂)

C. (m₁ + m₂)/ m₁. m₂. g

D. (m₁ + m₂)/2m₁. m₂. g

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4

The moment of inertia of a solid sphere of mass m and radius r is

A. 2mr2/3

B. 2mr2/5

C. mr2

D. mr2/2

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4

The maximum efficiency of a screw jack is

A. (1 - sinφ)/(1 + sinφ)

B. (1 + sinφ)/(1 - sinφ)

C. (1 - tanφ)/(1 + tanφ)

D. (1 + tanφ)/(1 - tanφ)

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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

A semicircular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi circular disc and horizontal surface is μ. This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will

A. Remain horizontal

B. Slant up towards direction of pull

C. Slant down towards direction of pull

D. None of the above

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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

The maximum acceleration of a particle moving with simple harmonic motion is

A. ω

B. ωr

C. ω2r

D. ω/r

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4

A framed structure is imperfect, if the numbers of members are __________ (2j - 3).

A. Equal to

B. Less than

C. Greater than

D. Either (B) or (C)

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4

In actual machines, mechanical advantage is __________ velocity ratio.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

A particle inside a hollow sphere of radius r, having coefficient of friction μ can rest up to height of

A. r/2

B. r/A

C. r/3

D. 0.134 r

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4

If a rigid body is in equilibrium under the action of three forces, then

A. These forces are equal

B. The lines of action of these forces meet in a point

C. The lines of action of these forces are parallel

D. Both (B) and (C) above

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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

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