The factional torque for square thread at the mean radius r while raising load W is given by
T = W.r tan(φ - α)
T = W.r tan(φ + α)
T = W.r tanα
T = W.r tanφ
Correct Answer :
B. T = W.r tan(φ + α)
Related Questions
The displacement of the D-slide valve is __________ the steam lap by a distance known as lead of the valve.
Greater than
Less than
Equal to
None of these
Which of the following statements regarding laws governing the friction between dry surfaces are correct?
The friction force is dependent on the materials of the contact surfaces.
The friction force is directly proportional to the normal force.
The friction force is independent of me area of contact.
All of the above
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
2
4
3
None of the above
When a mass of a critically damped single degree of freedom system is deflected from its equilibrium position and released, then it will
Return to equilibrium position without oscillation
Oscillate with increasing time period
Oscillate with decreasing amplitude
Oscillate with constant amplitude
The motion between a pair which takes place in __________ is known as incompletely constrained motion.
One direction only
Two directions only
More than one direction
None of these
The fundamental equation for correct steering is (where φ and α = Angle through which the axis of the outer wheel and inner wheel turns respectively, c = Distance between the pivots of the front axles, and d = Wheel base)
sinφ + sinα = b/c
cosφ - sinα = c/b
cotφ - cotα = c/b
tanφ + cotα = b/c
For the brake to be self locking, the force P at C shown in the below figure, should 
Be zero
Act in upward direction
Act in downward direction
None of these
In a screw jack, the effort required to lift the load W is given by (where α = Helix angle, and φ = Angle of friction)
P = W tan(α - φ)
P = W tan(α + φ)
P = W tan(φ - α)
P = W cos(α + φ)
The primary unbalanced force is maximum when the angle of inclination of the crank with the line of stroke is
0° and 90°
0° and 180°
90° and 180°
180° and 360°
In order to facilitate starting of locomotive in any position, the cranks of a locomotive with two cylinders, are placed at
45° to each other
90° to each other
120° to each other
180° to each other
A kinematic chain is known as a mechanism when
None of the links is fixed
One of the links is fixed
Two of the links are fixed
None of these
The tendency of a body to resist change from rest or motion is known as
Mass
Friction
Inertia
Resisting force
The ratio of the driving tensions for V-belts is __________ times that of flat belts. (Where β = Semi-angle of the groove)
sinβ
cosβ
cosecβ
secβ
A point on a connecting link (excluding end points) of a double slider crank mechanism traces a
Straight line path
Hyperbolic path
Parabolic path
Elliptical path
The Ackerman steering gear mechanism is preferred to the Davis steering gear mechanism, because
Whole of the mechanism in the Ackerman steering gear is on the back of the front wheels
The Ackerman steering gear consists of turning pairs
The Ackerman steering gear is most economical
Both (A) and (B)
Which one of the following can completely balance several masses revolving in different planes on a shaft?
A single mass in different planes
Two masses in any two planes
A single mass in one of the planes of the revolving masses
Two equal masses in any two planes
A mechanism consisting of four links is called a __________ mechanism.
Simple
Compound
Binary
None of these
In Meyer's expansion valve, the main valve is driven by an eccentric having an angle of advance from
10°-15°
15°-25°
25°-30°
30°-40°
The gear train usually employed in clocks is a
Simple gear train
Reverted gear train
Sun and planet gear
Differential gear
The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the left. The effect of gyroscopic couple on the aeroplane will be
To dip the nose and tail
To raise the nose and tail
To raise the nose and dip the tail
To dip the nose and raise the tail
When two links are connected by a pin joint, their instantaneous centre lies
On their point of contact
At the centre of curvature
At the centre of circle
At the pin joint
A spring controlled governor is found unstable. It can be made stable by
Increasing the spring stiffness
Decreasing the spring stiffness
Increasing the ball mass
Decreasing the ball mass
A thin circular disc is rolling with a uniform linear speed, along a straight path on a plane surface. Which of the following statement is correct in this regard?
All points of the disc have the same velocity
The centre of the disc has zero acceleration
The centre of the disc has centrifugal acceleration
The point on the disc making contact with the plane surface has zero acceleration
The centre of percussion is below the centre of gravity of the body and is at a distance equal to
h/kG
h²/kG
kG²/h
h × kG
The equation of free vibrations of a system is (d²x/dt²) +36 π²x, its natural frequency is
3 Hz
3π Hz
6 Hz
6π Hz
Which of the following is an inversion of a single slider crank chain?
Pendulum pump
Oscillating cylinder engine
Rotary internal combustion engine
All of these
The minimum periodic time of a compound pendulum is
(1/2π). √(kG/g)
(1/2π). √(2kG/g)
2π. √(kG/g)
2π. √(2kG/g)
A body is said to be under forced vibrations, when
There is a reduction in amplitude after every cycle of vibration
No external force acts on a body, after giving it an initial displacement
A body vibrates under the influence of external force
None of the above
The coriolis component of acceleration depends upon
Velocity of slider
Angular velocity of the link
Both (A) and (B)
None of these
A rotor supported at A and B carries two masses as shown in the below figure. The rotor is 
Dynamically balanced
Statically balanced
Statically and dynamically balanced
Not balanced