# Gyroscope - Mechanical Engineering (MCQ) questions and answers

1)   Calculate gyroscopic couple acting on a disc which has radius of 135 mm. Angular and precessional velocities are 15 rad/sec and 7 rad/sec respectively.
Assume density = 7810 kg/m3  and thickness of disc = 30 mm

a. 12.83 N-m
b. 10.99 N-m
c. 11 N-m
d. Incomplete data
 Answer  Explanation ANSWER: 12.83 N-m Explanation: No explanation is available for this question!

2)   Gyroscopic effect is not observed in which of the following actions performed by the ships?

a. Rolling
b. Pitching
c. Steering
d. All of the above
 Answer  Explanation ANSWER: Rolling Explanation: No explanation is available for this question!

3)   What is meant by pitching of ship?

a. up and down motion of bow and stern along transverse axis
b. up and down motion of bow and stern along longitudinal axis
c. up and down motion of port and starboard along transverse axis
d. none of the above
 Answer  Explanation ANSWER: up and down motion of bow and stern along transverse axis Explanation: No explanation is available for this question!

4)   Calculate reactive gyroscopic couple acting on rotating disc which is inclined at an angle of 1.5o. Mass moment of inertia about polar and diametral axis is 2.45 kg-m2 and 0.5 kg-m2 respectively. The disc rotates at an angular velocity of 130 rad/sec

a. 800.36 N-m
b. 862.36 N-m
c. 850.11 N-m
d. None of the above
 Answer  Explanation ANSWER: 862.36 N-m Explanation: No explanation is available for this question!

5)   What is the effect of reactive gyroscopic couple when aeroplane takes right turn and propeller rotates in clockwise direction?

a. The tail of the aeroplane is dipped and nose is raised
b. The tail of the aeroplane is raised and nose is dipped
c. Reactive gyroscopic couple has no effect when propeller rotates in clockwise direction
d. None of the above
 Answer  Explanation ANSWER: The tail of the aeroplane is raised and nose is dipped Explanation: No explanation is available for this question!

6)   What is the effect of reactive gyroscopic couple when an aeroplane takes a right turn and propeller rotates in anticlockwise direction?

a. The nose and tail of the aeroplane are in horizontal plane
b. The nose of the aeroplane is raised and tail is dipped
c. The nose of the aeroplane is dipped and tail is raised
d. None of the above
 Answer  Explanation ANSWER: The nose of the aeroplane is dipped and tail is raised Explanation: No explanation is available for this question!

7)   What is the gyroscopic couple acting on the disc which has mass moment of inertia equal to 0.02135 kg-m2. If disc has a speed of 500 rpm and is made to precess at 100 rpm.

a. 13.21 N-m
b. 11.70 N-m
c. 10.23 N-m
d. Incomplete data
 Answer  Explanation ANSWER: 11.70 N-m Explanation: No explanation is available for this question!

8)   Which of the following statements is/are false for active gyroscopic couple?

a. Reactive gyroscopic couple and active gyroscopic couple are opposite in direction
b. In right hand rule, curled fingers denote direction of precession
c. In active gyroscopic couple spin vector and precession vector are parallel to each other
d. All the statements are false
 Answer  Explanation ANSWER: In active gyroscopic couple spin vector and precession vector are parallel to each other Explanation: No explanation is available for this question!

9)   How is the direction of precession vector decided by right hand rule?

a. Thumb denotes direction of precession vector
b. Curled fingers denote direction of precession vector

 Answer  Explanation ANSWER: Thumb denotes direction of precession vector Explanation: No explanation is available for this question!

10)   Degree of freedom for gyroscope rotor is

a. 1
b. 2
c. 3
d. 5
 Answer  Explanation ANSWER: 3 Explanation: No explanation is available for this question!