The dynamic friction is the friction experienced by a body, when the body
The ratio of the actual damping coefficient to the critical damping coefficient is called damping factor.
The steering of a ship means
When a body moves with simple harmonic motion, the product of its periodic time and frequency is equal to
The tractive force in a locomotive with two cylinders is given by (where c = Fraction of reciprocating parts per cylinder, m = Mass of reciprocating parts, ω = Angular speed of crank, r = Radius of crank, and θ = Angle of inclination of crank to the line of stroke)
In a vibrating system, if the actual damping coefficient isN/m/s and critical damping coefficient isN/m/s, then logarithmic decrement is equal to
The radial distance of a tooth from the pitch circle to the bottom of the tooth is called
For high speed engines, the cam follower should move with
When the crank is at the inner dead centre, in a reciprocating steam engine, then the velocity of the piston will be
In a coupling rod of a locomotive, each of the four pairs is a __________ pair.
If ω/ωn is very high for a body vibrating under steady state vibrations, the phase angle for all values of damping factors, will tend to approach
The frictional torque transmitted in a multi-collared shaft is same as that of a single collared shaft.
The pair is known as a higher pair, when the relative motion between the elements of a pair is
In vibration isolation system, the transmissibility will be equal to unity, for all values of damping factor, if ω/ωn is
In a circular arc cam with roller follower, the acceleration in any position of the lift will depend only upon
The gears are termed as medium velocity gears, if their peripheral velocity is
The pressure angle of a cam is the angle between the direction of the follower motion and a normal to the
When the two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as a
The sliding pairs, turning pairs and screw pairs form lower pairs.
In order to give the primary balance of the reciprocating parts of a multi-cylinder in-line engines,
When the connection between the two elements is such that only required kind of relative motion occurs, it is known as self-closed pair.
The two links OA and OB are connected by a pin joint at O. If the link OA turns with angular velocity ω1 rad/s in the clockwise direction and the link OB turns with angular velocity ω2 rad/s in the clockwise direction, then the rubbing velocity at the pin joint O is (where r = Radius of the pin at O)
When the relation between the controlling force (Fc) and radius of rotation (r) for a spring controlled governor is Fc = ar + b, then the governor will be
A pair of friction discs is an example of rolling pair.
When a particle moves round the circumference of a circle of radius r with ω rad/s, then its maximum acceleration is ω2r.
The gear train usually employed in clocks is a
The Whitworth quick return motion mechanism is formed in a slider crank chain when the
If ω/ωn = 2, where co is the frequency of excitation and ωn is the natural frequency of vibrations, then the transmissibility of vibration will the
The factor which affects the critical speed of a shaft is
The frequency of damped vibrations with viscous damping is __________ the frequency of undamped vibrations.
In order to balance the reciprocating masses,
The two elements of a pair are said to form a __________ when they permit relative motion between them.
The static friction
The two elements of a pair are said to form a __________ when they permit relative motion between them.
A mass of 1 kg is attached to the end of a spring with a stiffness of 0.7 N/mm. The critical damping coefficient of this system is
The primary unbalanced force is maximum when the angle of inclination of the crank with the line of stroke is
A disturbing mass m1 attached to the rotating shaft may be balanced by a single mass m2 attached in the same plane of rotation as that of m1, such that (where r1 and r2 are the radii of rotation of m1 and m2 respectively)
The partial balancing of reciprocating parts in locomotives produces
Whitworth quick return motion mechanism consists of three turning pairs and one sliding pair.
In a screw jack, the effort required to lower the load W is given by
When the axes of the shafts, over which the gears are mounted, move relative to a fixed axis, then the train is known as reverted gear train.
A shaft has an attached disc at the centre of its length. The disc has its centre of gravity located at a distance of 2 mm from the axis of the shaft. When the shaft is allowed to vibrate in its natural bow-shaped mode, it has a frequency of vibration ofrad/s. When the shaft is rotated atr.p.m., it will whirl with a radius of
The cam follower generally used in automobile engines is
The acceleration of the particle moving with simple harmonic motion is inversely proportional to the displacement of the particle from the mean position.
In railway axle boxes, the bearing used is
The rotor of a ship rotates in clockwise direction when viewed from stern and the ship takes a right turn. The effect of gyroscopic couple acting on it will be to raise the stern and lower the bow.
An automobile steering gear is an example of
In under damped vibrating system, the amplitude of vibration
The swaying couple is maximum or minimum when the angle of inclination of the crank to the line of stroke (θ) is equal to
The rotor of a ship rotates in clockwise direction when viewed from stern and the ship takes a right turn. The effect of gyroscopic couple acting on it will be to raise the stern and lower the bow.