481. The two elements of a pair are said to form a __________ when they permit relative motion between them.
open pair
kinematic pair
✅ The correct answer is option B.
Theory of machines MCQs
482. The partial balancing of reciprocating parts in locomotives produces
hammer blow
swaying couple
variation in tractive force along the line of stroke
all of the above
✅ The correct answer is option D.
483. 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)
m.ω2.r cos θ
c.m.ω2.r sin θ
(1 – c)m.ω2.r(cos θ – sin θ)
m.ω2.r(cos θ – sin θ)
✅ The correct answer is option C.
484. In a circular arc cam with roller follower, the acceleration in any position of the lift will depend only upon
total lift, total angle of lift, minimum radius of cam and cam speed
radius of circular arc, cam speed, location of centre of circular arc and roller diameter
mass of cam follower linkage, spring stiffness and cam speed
total lift, centre of gravity of the cam and cam speed
✅ The correct answer is option A.
485. 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.
Right
Wrong
✅ The correct answer is option B.
486. 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
stable
unstable
isochronous
none of these
✅ The correct answer is option B.
487. 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
1.4 N-s/m
18.52 N-s/m
52.92 N-s/m
529.2 N-s/m
✅ The correct answer is option C.
488. When the crank is at the inner dead centre, in a reciprocating steam engine, then the velocity of the piston will be
minimum
zero
maximum
none of these
✅ The correct answer is option B.
489. 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
0.5
1
1.5
2
✅ The correct answer is option B.
490. An automobile steering gear is an example of
sliding pair
rolling pair
lower pair
higher pair
✅ The correct answer is option C.