1. The pitching of the ship is assumed to take place with which of the following motion?
a) Constant acceleration
b) Simple Harmonic Motion
c) Cycloidal
d) Uniform Velocity
Explanation: Motion of the spin axis about transverse axis undergoes SHM, the motion tends to be longitudinal oscillatory rotation about the transverse axis.
2. Maximum couple during pitching is given by : (ω: angular velocity of rotor & ωpmax: Maximum angular velocity of precession).
a) Cmax = I.(ωpmax)2
b) Cmax = I.(ω)2
c) Cmax = I. ω. ωpmax
d) Cmax = I2. ω. ωpmax
Explanation: Maximum couple depends on both angular velocity of rotor and angular velocity of precession, therefore it is maximum when ωp is maximum.
3. During upward pitching, Gyroscopic couple will tend to move the ship towards ________
a) Star-board
b) Port side
c) Ship movement is unaffected by upward pitching
d) Left side
Explanation: During upward pitching, angular displacement of axis of spin from mean position is positive i.e Anti clockwise, therefore gyroscopic couple moves it towards right side or star board.
4. During downward pitching, Gyroscopic couple will tend to move the ship towards ________
a) Star-board
b) Port side
c) Ship movement is unaffected by upward pitching
d) Right side
Explanation: During downward pitching, angular displacement of axis of spin from mean position is negative i.e Clockwise, therefore gyroscopic couple moves it towards left side or port-side
5. If the movement of the ship were to occur about a vertical plane about a parallel axis then which of the following factors will be affected while pitching?
a) Upward pitch
b) Downward pitch
c) Pitching will not occur
d) Change in angular velocity of rotor
Explanation: For pitching to occur, motion should be about a vertical plane about a Transverse axis, else the motion will not be considered pitching. If the movement is about the parallel axis then it is called Rolling.
6. What will be the effect of a gyroscopic couple if the axis of precession and axis of spin become parallel?
a) No effect
b) Pitching
c) Steering effect
d) No motion
Explanation: For a gyroscope couple effect to occur the axis of precession should always be perpendicular to the axis of spin, if this condition is not fulfilled then no effect will take place.
7. Which of the following is known as the axis of precession?
a) Latitudinal axis
b) Longitudinal axis
c) Reverse axis
d) Axis of spin
Explanation: The longitudinal axis is known as the axis of precession as it is along the direction of the acting force, about which the precession occurs
8. The axis of precession is parallel to axis of spin during rolling for only a selected few positions.
a) True
b) False
Explanation: The axis of precession is parallel to the axis of spin during rolling for all positions, if this condition is not met then there can be other effects like pitching which can occur.
9. Which of the following would change during rolling of a navalship?
a) Angular velocity of precession
b) Angular acceleration of precession
c) Angular velocity of spin
d) No change occurs
Explanation: Since the axis of precession is parallel to the axis of spin during rolling, the gyroscopic couple causes no change in motion of the ship, Hence no change occurs
10. The gyroscope couple does not cause an effect on a naval ship during which of these motions?
a) Pitching
b) Steering
c) Rolling
d) Lifting
Explanation: There is no such motion as “lifting” hence no effect exists, while the effect of a gyroscopic couple is pronounced during pitching steering and rolling.