1. The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the left. The effect of gyroscopic couple on the aeroplane will be
a) to dip the nose and tail
b) to raise the nose and tail
c) to raise the nose and dip of the tail
d) to dip the nose and raise the tail
The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the left. The effect of gyroscopic couple on the aeroplane will be to raise the nose and dip of the tail.
The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the right. The effect of gyroscopic couple on the aeroplane will be to dip the nose and raise the tail
2. The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the right. The effect of gyroscopic couple on the aeroplane will be to dip the nose and raise the tail
a) True
b) false
Explanation: The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the left. The effect of gyroscopic couple on the aeroplane will be to raise the nose and dip of the tail.
The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the right. The effect of gyroscopic couple on the aeroplane will be to dip the nose and raise the tail
3. The steering of a ship mean
a) movement of a complete ship up and down in vertical plane about transverse axis
b) turning of a complete ship in a curve towards right or left, while it moves forward
c) rolling of a complete ship side-ways
d) none of the mentioned
Explanation: The steering is the turning of a complete ship in a curve towards right or left, while it moves forward.
4. The rolling of a complete ship side-ways is known as pitching of a ship
a) True
b) False
Explanation: The pitching is the movement of a complete ship up and down in a vertical plane about transverse axis.
5. The rotor of a ship rotates in clockwise direction when viewed from stern and the ship takes a left turn. The effect of gyroscopic couple acting on it will be
a) to raise the bow and stern
b) to lower the bow and stern
c) to raise the bow and lower the stern
d) to raise the stern and lower the bow.
Explanation:The rotor of a ship rotates in clockwise direction when viewed from stern and the ship takes a left turn. The effect of gyroscopic couple acting on it will be to raise the bow and lower the stern.
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
6. 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.
a) True
b) false
Explanation: The rotor of a ship rotates in clockwise direction when viewed from stern and the ship takes a left turn. The effect of gyroscopic couple acting on it will be to raise the bow and lower the stern.
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
7. The pitching of a ship is assumed to take place with simple harmonic motion.
a) True
b) False
Explanation: True
8. When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be
a) to move the ship towards star-board
b) to move the ship towards port side
c) to raise the bow and lower the stern
d) to raise the stern and lower the bow
Explanation: When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be to move the ship towards star-board.
When the pitching of a ship is downward, the effect of gyroscopic couple, is to turn the ship towards port side.
9. A uniform disc of diameter 300 mm and of mass 5 kg is mounted on one end of an arm of length 600 mm. The other end of the arm is free to rotate in a universal bearing. If the disc rotates about the arm with a speed of 300 r.p.m. clockwise, looking from the front, with what speed will it precess about the vertical axis?
a) 14.7 rad/s
b) 15.7 rad/s
c) 16.7 rad/s
d) 17.7 rad/s
Explanation: Given: d = 300 mm or r = 150 mm = 0.15 m ; m = 5 kg ; l = 600 mm = 0.6 m ;
N = 300 r.p.m. or ω = 2π × 300/60 = 31.42 rad/s
We know that the mass moment of inertia of the disc, about an axis through its centre of gravity and perpendicular to the plane of disc,
I = m.r2/2 = 5(0.15)2/2 = 0.056 kg-m2
and couple due to mass of disc, C = m.g.l = 5 × 9.81 × 0.6 = 29.43 N-m
Let ωP = Speed of precession
We know that couple (C),
29.43 = I.ω.ωP = 0.056 × 31.42 × ωP = 1.76 ωP
ωP = 29.43/1.76 = 16.7 rad/s
10. An aeroplane makes a complete half circle of 50 metres radius, towards left, when flying at 200 km per hr. The rotary engine and the propeller of the plane has a mass of 400 kg and a radius of gyration of 0.3 m. The engine rotates at 2400 r.p.m. clockwise when viewed from the rear. Find the gyroscopic couple on the aircraft.
a) 10.046 kN-m
b) 11.046 kN-m
c) 12.046 kN-m
d) 13.046 kN-m
Explanation: Given : R = 50 m ; v = 200 km/hr = 55.6 m/s ; m = 400 kg ; k = 0.3 m ;
N = 2400 r.p.m. or ω = 2π × 2400/60 = 251 rad/s
We know that mass moment of inertia of the engine and the propeller,
I = mk2 = 36 kg-m2
and angular velocity of precession,
ωP = v/R = 55.6/50 = 1.11 rad/s
We know that gyroscopic couple acting on the aircraft,
C = I. ω. ωP = 36 × 251.4 × 1.11 = 100 46 N-m
= 10.046 kN-m