Engineering Questions with Answers - Multiple Choice Questions

# Machine Dynamics MCQ – Stability of a Four Wheel drive Moving in a Curved Path

1 - Question

Which of the following relation is correct regarding the net gyroscope couple C acting on a four wheel vehicle?
a) ωw.ωp (4 Iw ± G.Ie)2
b) ωw.ωp (4 Iw* G.Ie)
c) ωw.ωp (4 Iw ± G.Ie)
d) ωw2(4 Iw ± G.Ie)

Explanation: When a four wheeled vehicle undergoes a motion along a curved path, the gyroscope couple acts on the vehicle. This effect depends on angular velocities of precession & wheels and moment of inertia of wheels and rotating parts of engine.

2 - Question

The positive sign is used to determine the gyroscope couple in which of the following cases?
a) When the wheels and rotating parts of the engine rotate in the same direction
b) When the wheels and rotating parts of the engine rotate in the opposite direction
c) When the precession is clockwise
d) When the precession is anticlockwise

Explanation: The positive sign is used when the wheels and rotating parts of the engine rotate in the same direction. If the rotating parts of the engine revolve in opposite direction, then negative sign is used.

3 - Question

If the net gyroscope couple is negative then which of the following is true?
a) The reaction will be vertically downwards on the outer wheels and vertically upwards on the inner wheels
b) The reaction will be vertically upwards on the outer wheels and vertically downwards on the inner wheels
c) The reaction will be vertically downwards on the outer wheels and vertically downwards on the inner wheels
d) The reaction will be vertically upwards on the outer wheels and vertically upwards on the inner wheels

Explanation: A negative gyroscope couple would result in opposite direction of the reaction from the ground in the wheels of the vehicle.

4 - Question

The relation between overturning couple and height of centre of gravity is given by_______
a) Co = Fcxh
b) Co = Mv2xh/R
c) Co = Mv2 * (h/R)2
d) Co = Mv2 * h/R2

Explanation: Centrifugal force is given by : Fc = (Mv2)/R and the overturning couple is the cross product of h and Fc.

5 - Question

In order to maintain contact between inner wheel and ground the sum of vertical reactions at each of the outer and inner wheels should be less than______
a) W
b) W/2
c) W/4
d) W/3

Explanation: The total vertical reaction at each of the inner wheel will be negative if the sum of vertical reactions at each of the outer and inner wheels is less than W/2.

6 - Question

Let x be the track width of the vehicle, then which of the following expression is correct for vertical reaction Q at the two outer or inner wheels?
a) Q = (Mv2. h)/ (R.x)
b) Q = (Mv2)/ R
c) Q = Mv2. x/ (R.h)
d) Q = (Mv2)/ (x)

Explanation: Centrifugal force is given by : Fc = (Mv2)/R and the overturning couple is the cross product of h and Fc, and Q=Co/x. Therefore Q = (Mv2.h)/ (R .x)

7 - Question

The overturning couple acting on the four wheeler vehicle is balanced by which of the following forces?
a) Centripetal force
b) Centrifugal force
c) Vertical reactions
d) Horizontal reactions

Explanation: Since the overturning couple tends to overturn the vehicle upside down about a horizontal plane, the vertical reactions provide stability and helps in preventing the overturn.

8 - Question

Overturning couple is independent of the track width.
a) False
b) True

Explanation: The overturning is the cross product of height of center of gravity and the centrifugal force. Since the centrifugal force does not depend on the track width, the overturning couple is independent of the track width.

9 - Question

Assuming that a vehicle is taking a left turn, The gyroscopic couple acting on the vehicle has a tendency to _____ the inner wheels and ____ the outer wheels.
a) Press, Lift
b) Lift, Press
c) Press, Press
d) Lift, Lift

Explanation: While taking a left turn, a four wheel vehicle undergoes the action of a gyroscopic couple which has an effect on inner and outer wheels. This effect results in lifting of inner wheel and pressing of the outer wheel. This prevents the overturning of vehicle.

10 - Question

Which of the following factor is not responsible for the stability of a 4 wheel vehicle while negotiating a turn?
a) Pitching
b) Reaction due to weight of Vehicle
c) Effect of Gyroscopic couple due to Wheel
d) Effect of Gyroscopic Couple due to Engine