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4

The dynamic friction is the friction experienced by a body, when the body

A. Is in motion

B. Is at rest

C. Just begins to slide over the surface of the other body

D. None of the above

Correct Answer :

A. Is in motion


Related Questions

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4

Kinematic pairs are those which have

A. Point or line contact between the two elements when in motion

B. Surface contact between the two elements when in motion

C. Elements of pairs not held together mechanically

D. Two elements that permit relative motion

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4

The frictional torque transmitted by a cone clutch is same as that of

A. Flat pivot bearing

B. Flat collar bearing

C. Conical pivot bearing

D. Truncated conical pivot bearing

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4

Pitch point on a cam is

A. Any point on pitch curve

B. The point on cam pitch curve having the maximum pressure angle

C. Any point on pitch circle

D. The point on cam pitch curve having the minimum pressure angle

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4

Which one of the following is an exact straight line mechanism using lower pairs?

A. Watts mechanism

B. Grasshopper mechanism

C. Roberts mechanism

D. Peaucelliers mechanism

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4

When the axes of the first and last wheels are coaxial, then the train is known as

A. Simple train of wheels

B. Compound train of wheels

C. Reverted gear train

D. Epicyclic gear train

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4

The natural frequency of free longitudinal vibrations is equal to (where m = Mass of the body, s = Stiffness of the body, and δ = Static deflection of the body)

A. 1/2π × √(s/m)

B. 1/2π × √(g/δ)

C. 0.4985/√δ

D. Any one of these

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4

A fixed gear having 200 teeth is in mesh with another gear having 50 teeth. The two gears are connected by an arm. The number of turns made by the smaller gear for one revolution of arm about the centre of bigger gear is

A. 2

B. 4

C. 3

D. None of the above

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4

For an involute gear, the ratio of base circle radius and pitch circle radius is equal to

A. sinφ

B. cosφ

C. secφ

D. cosecφ

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4

When the radius of rotation of balls __________ as the equilibrium speed increases, the governor is said to be unstable.

A. Remains constant

B. Decreases

C. Increases

D. None of these

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4

The axis of precession is __________ to the plane in which the axis of spin is going to rotate.

A. Parallel

B. Perpendicular

C. Both A and B

D. None of these

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4

A pantograph is a mechanism with

A. Lower pairs

B. Higher pairs

C. Rolling pairs

D. Turning pairs

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4

In a hydrodynamic journal bearing, there is

A. A very thin film of lubricant between the journal and the bearing such that there is contact between the journal and the bearing

B. A thick film of lubricant between the journal and the bearing

C. No lubricant between the journal and the bearing

D. A forced lubricant between the journal and the bearing

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4

When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be

A. To move the ship towards starboard

B. To move the ship towards port side

C. To raise the bow and lower the stern

D. To raise the stern and lower the bow

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4

In automobiles the power is transmitted from gear box to differential through

A. Bevel gear

B. Universal joint

C. Hooke's joint

D. Knuckle joint

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4

Klein's construction gives a graphic construction for

A. Slider-crank mechanism

B. Velocity polygon

C. Acceleration polygon

D. Four bar chain mechanism

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4

When the body is suspended at the point of suspension, its periodic time and frequency will be ________ as compared to the body suspended at the point of percussion.

A. Same

B. Two times

C. Four times

D. None of these

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4

The frictional torque transmitted in a truncated conical pivot bearing, considering uniform pressure, is

A. (1/2). μ W cosecα (r₁ + r₂)

B. (2/3). μ W cosecα (r₁ + r₂)

C. (1/2). μ W cosecα [(r₁³ - r₂³)/(r₁² - r₂²)]

D. (2/3). μ W cosecα [(r₁³ - r₂³)/(r₁² - r₂²)]

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4

The Grubler's criterion for determining the degrees of freedom (n) of a mechanism having plane motion is (where l = Number of links, and j = Number of binary joints)

A. n = (l -1) - j

B. n = 2(l - 1) - 2j

C. n = 3(l - 1) - 2j

D. n = 4(l - 1) - 3j

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4

To connect two parallel and coplanar shafts the following type of gearing is used

A. Spur gear

B. Bevel gear

C. Spiral gear

D. None of the above

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4

A fixed gear having 200 teeth is in mesh with another gear having 50 teeth. The two gears are connected by an arm. The number of turns made by the smaller gear for one revolution of arm about the centre of bigger gear is

A. 2

B. 3

C. 4

D. 5

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4

The two parallel and coplanar shafts are connected by gears having teeth parallel to the axis of the shaft. This arrangement is known as

A. Spur gearing

B. Helical gearing

C. Bevel gearing

D. Spiral gearing

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4

Which of the following is false statement in respect of differences between machine and structure?

A. Machines transmit mechanical work, whereas structures transmit forces

B. In machines, relative motion exists between its members, whereas same does not exist in case of structures

C. Machines modify movement and work, whereas structures modify forces

D. Efficiency of machines as well as structures is below 100%

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4

ABCD is a four bar mechanism in which AB = 310 mm and CD = 450 mm. AB and CD are both perpendicular to the fixed link AD, as shown in the below figure. If the velocity of B at this condition is v. Then the velocity of C is

A. v

B. (2/3). v

C. (3/2). v

D. (9/4). v

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4

The velocity of any point in mechanism relative to any other point on the mechanism on velocity polygon is represented by the line

A. Joining the corresponding points

B. Perpendicular to line as per (A)

C. Not possible to determine with these data

D. At 45° to line as per (A)

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4

The face of the tooth is the

A. Surface of the top of tooth

B. Surface of tooth above the pitch surface

C. Width of tooth below the pitch surface

D. Width of tooth measured along the pitch circle

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4

The displacement of the D-slide valve is __________ the steam lap by a distance known as lead of the valve.

A. Greater than

B. Less than

C. Equal to

D. None of these

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4

When a mass of a critically damped single degree of freedom system is deflected from its equilibrium position and released, then it will

A. Return to equilibrium position without oscillation

B. Oscillate with increasing time period

C. Oscillate with decreasing amplitude

D. Oscillate with constant amplitude

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4

The ratio of the number of teeth to the pitch circle diameter in millimetres, is called

A. Circular pitch

B. Diametral pitch

C. Module

D. None of these

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4

The example of spherical pair is

A. Bolt and nut

B. Lead screw of a lathe

C. Ball and socket joint

D. Ball bearing and roller bearing

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4

A cam mechanism imparts following motion

A. Rotating

B. Oscillating

C. Reciprocating

D. All of the above