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4

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

A. Towards the wall at its upper end

B. Away from the wall at its upper end

C. Downward at its upper end

D. Upward at its upper end

Correct Answer :

D. Upward at its upper end


Related Questions

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4

Pick up wrong statement about friction force for dry surfaces. Friction force is

A. Proportional to normal load between the surfaces

B. Dependent on the materials of contact surface

C. Proportional to velocity of sliding

D. Independent of the area of contact surfaces

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4

The centre of gravity of a uniform lamina lies at

A. The centre of heavy portion

B. The bottom surface

C. The midpoint of its axis

D. All of the above

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4

When a body of mass moment of inertia I (about a given axis) is rotated about that axis with an angular velocity to, then the kinetic energy of rotation is

A.

B. 2

C. 0.5 Iω

D. 0.5 Iω2

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4

The power developed by a body acted upon by a torque T Newton metre (N - m) and revolving at ω radian/s is given by

A. T.ω (in watts)

B. T.ω/60 (in watts)

C. T.ω/75 (in kilowatts)

D. T.ω/4500 (in kilowatts)

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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 amplitude is always __________ radius of the circle.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

A force acting on a body may

A. Change its motion

B. Balance the other forces acting on it

C. Retard its motion

D. All of the above

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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 centre of percussion is below the centre of gravity of the body and is at a distance equal to

A. h/kG

B. h2/kG

C. kG2/h

D. h × kG

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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

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

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

The C.G. of a right circular solid cone of height h lies at the following distance from the base

A. h/2

B. J/3

C. h/6

D. h/4

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4

Moment of inertia of a triangular section of base (b) and height (h) about an axis through its base, is

A. bh3/4

B. bh3/8

C. bh3/12

D. bh3/36

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4

The rate of change of displacement of a body is called

A. Velocity

B. Acceleration

C. Momentum

D. None of these

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4

The necessary condition for forces to be in equilibrium is that these should be

A. Coplanar

B. Meet at one point

C. Both (A) and (B) above

D. All be equal

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4

Which of the following statement is correct?

A. The algebraic sum of the forces, constituting the couple is zero

B. The algebraic sum of the forces, constituting the couple, about any point is the same

C. A couple cannot be balanced by a single force but can be balanced only by a couple of opposite sense

D. All of the above

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4

The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as

A. Static friction

B. Dynamic friction

C. Limiting friction

D. Coefficient of friction

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4

Which of the following statement is incorrect?

A. A force acting in the opposite direction to the motion of the body is called force of friction

B. The ratio of the limiting friction to the normal reaction is called coefficient of friction

C. A machine whose efficiency is 100% is known as an ideal machine

D. The velocity ratio of a machine is the ratio of load lifted to the effort applied

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4

The moment of inertia of a square of side a about its diagonal is

A. a2/8

B. a3/12

C. a4/12

D. a4/16

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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

When a body falls freely under gravitational force, it possesses __________ weight.

A. No

B. Minimum

C. Maximum

D. None of these

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4

The angle which an inclined plane makes with the horizontal when a body placed on it is about to move down is known as angle of

A. Friction

B. Limiting friction

C. Repose

D. Kinematic friction

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4

The resolved part of the resultant of two forces inclined at an angle θ in a given direction is equal to

A. The algebraic sum of the resolved parts of the forces in the given direction

B. The sum of the resolved parts of the forces in the given direction

C. The difference of the forces multiplied by the cosine of θ

D. The sum of the forces multiplied by the sine of θ

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4

If the masses of both the bodies, as shown in the below figure, are doubled, then the acceleration in the string will be

A. Same

B. Half

C. Double

D. None of these

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4

In a screw jack, the effort required to lift the load is given by (where W = Load lifted, α = Helix angle, and φ = Angle of friction.)

A. P = W tan (α - φ)

B. P = W tan (α + φ)

C. P = W tan (φ - α)

D. P = W cos (α + φ)

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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 energy possessed by a body, for doing work by virtue of its position, is called

A. Potential energy

B. Kinetic energy

C. Electrical energy

D. Chemical energy

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4

A rubber ball is dropped from a height of 2 m. If there is no loss of velocity after rebounding, the ball will rise to a height of

A. 1 m

B. 2 m

C. 3 m

D. 4 m

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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