GATE ME topic:theory-machines PYQs & Answers — Page 4

Questions 31–40 of 46. Imported answers require independent review unless marked reviewed.

In a four bar planar mechanism shown in the figure, AB = 5 cm, AD = 4 cm and DC = 2 cm. In the configuration shown, both AB and DC are perpendicular to AD. The bar AB rotates with an angular velocity of 10 rad/s. The magnitude of angular velocity (in rad/s) of bar DC at this instant is

Diagram for Mechanical Engineering question 30

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The rotor of a turbojet engine of an aircraft has a mass 180 kg and polar moment of inertia 10 kg m² about the rotor axis. The rotor rotates at a constant speed of 1100 rad/s in the clockwise direction when viewed from the front of the aircraft. The aircraft while flying at a speed of 800 km per hour takes a turn with a radius of 1.5 km to the left. The gyroscopic moment exerted by the rotor on the aircraft structure and the direction of motion of the nose when the aircraft turns, are

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1629.6 N·m and the nose goes up

1629.6 N·m and the nose goes down

162.9 N·m and the nose goes up

162.9 N·m and the nose goes down

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The crank of a slider-crank mechanism rotates counter-clockwise (CCW) with a constant angular velocity

, as shown.

Diagram for Mechanical Engineering question 36

Assume the length of the crank to be

Using exact analysis, the acceleration of the slider in the

-direction, at the instant shown, where the crank is parallel to

-axis, is given by

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Two masses

and

having mass

and

, respectively, lying in the plane of the figure shown, are rigidly attached to a shaft which revolves about an axis through O perpendicular to the plane of the figure. The radii of rotation of the masses

and

are

and

, respectively. The angle between lines OA and OB is 90°. If

and

, then the balance mass to be placed at a radius of 200 mm is ______ kg (round off to two decimal places).

Diagram for Mechanical Engineering question 38

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A four bar mechanism is shown in the figure. The link numbers are mentioned near the links. Input link 2 is rotating anticlockwise with a constant angular speed

. Length of different links are:

The magnitude of the angular speed of the output link 4 is

at the instant when link 2 makes an angle of 90° with

as shown. The ratio

is ______ (round off to two decimal places).

Diagram for Mechanical Engineering question 39

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A uniform disc with radius

and a mass of

kg is mounted centrally on a horizontal axle of negligible mass and length of 1.5r. The disc spins counter-clockwise about the axle with angular speed

, when viewed from the right-hand side bearing, Q. The axle precesses about a vertical axis at

in the clockwise direction when viewed from above. Let

and

(positive upwards) be the resultant reaction forces due to the mass and the gyroscopic effect, at bearings P and Q, respectively. Assuming

and

, the ratio of the larger to the smaller bearing reaction force (considering appropriate signs) is ______.

Diagram for Mechanical Engineering question 41

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A frictionless gear train is shown in the figure. The leftmost 12-teeth gear is given a torque of 100 N-m. The output torque from the 60-teeth gear on the right in N-m is

Diagram for Mechanical Engineering question 6

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500

200

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For an Oldham coupling used between two shafts, which among the following statements are correct? I. Torsional load is transferred along shaft axis. II. A velocity ratio of 1:2 between shafts is obtained without using gears. III. Bending load is transferred transverse to shaft axis. IV. Rotation is transferred along shaft axis.

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I and III

I and IV

II and III

II and IV

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A four bar mechanism is made up of links of length 100, 200, 300 and 350 mm. If the 350 mm link is fixed, the number of links that can rotate fully is __________.

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An epicyclic gear train is shown in the figure below. The number of teeth on the gears A, B and D are 20, 30 and 20, respectively. Gear C has 80 teeth on the inner surface and 100 teeth on the outer surface. If the carrier arm AB is fixed and the sun gear A rotates at 300 rpm in the clockwise direction, then the rpm of D in the clockwise direction is

Your answerChoose one option.

240

−240

375

−375

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GATE ME topic:theory-machines PYQs

Question 30

Question 31

Question 36

Question 38

Question 39

Question 41

Question 6

Question 8

Question 20

Question 30