# Vehicle Dynamics MCQ (Multiple Choice Questions)

1. In which kind of vibration no external variable force applied to the system?
a) Free vibration
b) Forced vibration
c) Forced damped vibration
d) Simple harmonic vibration

Explanation: No external force is applied to the system in free vibration. An external force is applied to the system in forced vibration which determines the period of the vibration. Energy is lost in forced damped vibration by a damping agent. In simple harmonic vibration, displacements from the mean position with respect to time are described by a single sine function.

2. Which kind of vibration has an irregular time period and amplitude?
a) Simple harmonic vibration
b) Periodic vibration
d) Random vibration

Explanation: When oscillations in a system are sustained but irregular in period and amplitude then it is a random vibration. Simple harmonic vibrations are sinusoidal. Steady-state vibrations have equal displacements from mean positions which are recurring. Periodic vibrations take place in equal time intervals.

3. What is the third derivative of displacement with respect to time?
a) acceleration
b) jerk
c) velocity
d) jounce

Explanation: Jerk is the rate of change of acceleration. It is the third derivative of displacement with respect to time. Velocity and acceleration are the first and second derivative of displacement respectively. Jounce is the rate of change of jerk.

4. In forced vibration, transmissibility is the ratio of transmitted force to the applied force.
a) True
b) False

Explanation: Transmissibility refers to the magnitude of force transmitted to the base from a vibrating source excited by an external force. This concept forms one of the bases of suspension design.

5. A prismatic joint has 2 degrees of freedom.
a) True
b) False

Explanation: A prismatic joint only allows for translation or linear motion. Hence, it has only one degree of freedom.

6. How many degrees of freedom does the telescopic shock absorbers of bikes have?
a) 2
b) 3
c) 1
d) 4

Explanation: Telescopic shock absorbers only allow translational motion. Therefore, it has only one degree of freedom. Cylindrical joints have 2 degrees of freedom. A higher degree of freedom system with springs and masses.

7. The change of the load produced by the spring per unit deflection is called as _____
a) spring rate
b) ride rate
c) deflection rate

Explanation: Spring rate is the change of the load produced by a spring per unit deflection. It is taken as the mean between loading and unloading at a certain load. Ride rate is the change in the wheel load per unit deflection of the sprung mass, measured at the tire contact patch with respect to the ground.

8. What is the term given for all the weight supported by the suspension?
a) Suspended weight
c) Free weight
d) Sprung weight

Explanation: Sprung weight is all the weight of the vehicle supported by the suspension system. This is inclusive of the weight of the suspension system too.

9. Vehicle suspension systems are _____
a) undamped
b) linear
c) damped
d) simple harmonic

Explanation: Suspension systems must lose energy to reduce the amplitude of the oscillations produced by the road. Hence, they are damped. Undamped vibratory systems do not lose energy and the amplitude of the oscillation remains constant. In linear vibratory systems, all the variable forces are directly proportional to displacement or its derivative with respect to time. Simple harmonic systems are sinusoidal.

10. S.I unit of spring rate is _____
a) N/m2
b) N/m
c) N/m3
d) N

Explanation: Spring rate is the change of the load produced by a spring per unit deflection. The unit of load or force is N and the unit of deflection or displacement is m, so the unit of spring rate is N/m. The unit of pressure is N/m2.

11. What is the tire section height?
a) half the difference between the tire outside diameter and nominal rim diameter
b) difference between the tire outside diameter and nominal rim diameter
c) twice the difference between the tire outside diameter and nominal rim diameter
d) thrice the difference between the tire outside diameter and nominal rim diameter

Explanation: Tire section height is half the difference between the tire outside diameter and nominal rim diameter. It is used to calculate the aspect ratio of a tire.

12. What is the component of force in the y-direction in the Vehicle Fixed Coordinate System?
a) Transverse force
b) Longitudinal force
c) Side force
d) Normal force

Explanation: Sideforce is the component of force in the y-direction. The longitudinal force acts in the x-direction and the normal force acts in the z-direction.

13. What is the vehicle roll angle?
a) the angle between the vehicle x-axis and the ground plane
b) the angle between the vehicle y-axis and the ground plane
c) the angle between the vehicle z-axis and the ground plane
d) the angle between the vehicle y-axis and the vertical plane

Explanation: The angle between the vehicle x-axis and the ground plane is the vehicle roll angle. The vehicle pitch angle is the angle between the vehicle x-axis and the ground plane.

14. What is the angular velocity of the vehicle about the z-axis?
a) Yaw velocity
b) Pitch velocity
c) Roll velocity
d) Spin velocity

Explanation: Yaw velocity is measured about the z-axis. Its S.I unit is radian/second. It is a measure of the angular speed at which the car turns about its z-axis while cornering. Pitch velocity is about the y-axis and roll velocity is about the x-axis.

15. A driver driving a car is a _____
a) Closed-loop system
b) Open-loop system
c) Loop system
d) Output system

Explanation: A driver driving a car is a closed-loop system. The driver provides the input to the vehicle which produces the output. The output is fed back to the driver. Open-loop systems have no feedback.

## Vehicle Dynamics MCQ on Basic Terminologies

16. What is the limit of ride frequency?
a) below 5 Hz
b) between 20 – 20000 Hz
c) above 20000 Hz
d) above 50 Hz

Explanation: Ride refers to the low-frequency vibrations of the sprung mass of the vehicle when considered as a rigid body. It consists of vibrations below 5 Hz. 20 – 20000 Hz is the human auditory frequency range. Above 20000 Hz is ultrasonic frequency.

17. The angle of inclination of the wheels with respect to the vertical plane when the vehicle is seen from the front view?
a) Tilt angle
b) Inclination angle
c) Spin angle
d) Camber angle

Explanation: Camber angle is the inclination of the wheel plane with respect to the vertical. It is taken as positive when the wheel is tilted away from the vertical plane and vice versa.

18. What is the lateral distance between the centers of tire contact for a pair of wheels called?
a) Wheel width
b) Wheel track
c) Wheelbase
d) Wheel length

Explanation: Wheel track also called wheel tread or track width is measured laterally between the center of tire contact for a pair of wheels. The wheelbase is the distance between the front and the rear center of tire contact.

19. Track width is measured along the y-axis according to the Vehicle Fixed Coordinate System.
a) True
b) False

Explanation: Track width is the lateral distance between the tire contact center of a pair of wheels. Lateral distances are measured in the direction lateral to the vehicle which is represented by the y-axis.

20. Wheel center is the point where the spin axis of the wheel intersects the vertical plane.
a) True
b) False

Explanation: Wheel center is the point where the spin axis of the wheel intersects the wheel plane. The wheel plane is the central plane of the tire normal to the spin axis.

21. What is the maximum displacement permitted by the suspension system in compression of the vehicle with respect to the wheel center?
a) Dynamic clearance
b) Static clearance
c) Ride clearance

Explanation: Ride clearance is the maximum displacement permitted by the suspension system in compression of the vehicle with respect to the wheel center. Sports car have very low ride clearance to reduce drag and lift. Off-road trucks have high clearance to negotiate obstacles.

22. Static toe is measured in _____
a) mm
b) degrees
d) m

Explanation: Static toe of a pair of wheels is the difference between the transverse distances between the wheel planes. This is taken at the rear and front extreme points of the tire. It is measured in mm.

23. Which is the instantaneous center in the transverse plane through the wheel center of the wheel about which it moves relative to the sprung mass?
a) Motion center
b) Path center
c) Oscillating center
d) Swing center

Explanation: Swing center is an instantaneous center in the transverse plane through any pair of wheel centers. The wheel moves about this point relative to the sprung mass.

24. What term is used for oscillation of the steerable wheels about their steering axis due to an external force?
a) Wheel oscillation
b) Wheel wobble
c) Tramp
d) Wheel flutter

Explanation: Wheel flutter is the forced oscillation of the wheels about their steering axis. Tramp refers to an out of phase wheel hop of a wheel pair. Wheel wobble is a self-excited oscillation of wheels about their steering axis, normally occurring in phase.

25. Wheel camber is measured in _____
a) degrees
b) mm
c) m
d) m/s

Explanation: Wheel camber is an angular measurement. It is measured in degrees. It is the tilt of the wheel with respect to the transverse vertical plane, when the vehicle is observed from the front view.

26. What is the vehicle motion resulting from an unwanted force called?
a) Random response
b) Steering response
c) Disturbance response
d) Turbulence response

Explanation: Disturbance response is the vehicle motion resulting from an unwanted force like wind or vertical road displacement. The steering response is vehicle motion arising from the steering.

27. Response tests can be used to determine the _____ and control characteristics of a vehicle.
a) speed
b) stability
c) acceleration
d) design

Explanation: Vehicle motion which arises from an external or an internal input is called the vehicle response. It is a major determinant of vehicle stability during the ride and its control characteristics.

28. What kind of load transfer occurs during braking?

Explanation: Due to inertial effects, the load shifts to the front axle while braking. This happens in the longitudinal direction. Lateral load transfer occurs during cornering.

29. What is the imaginary point about which the vehicle body oscillates during cornering called?
a) Turning center
b) Oscillation center
c) Sway center
d) Roll center

Explanation: Roll center lies in the transverse vertical plane. Any lateral force applied to the roll center will not produce suspension roll. Very high roll center height may result in a rollover during high speed turning.

30. ABS stands for _____
a) Antilock Braking System
b) Automatic Braking System
c) Alternate Braking System
d) Antiskid Braking System

Explanation: ABS is a common component in the braking system of most modern-day cars. It is a closed-loop system which prevents the wheel lock-up during panic braking or braking in low traction. It is used to maintain the directional stability of the vehicle.

## Vehicle Dynamics MCQ on Approach To Vehicle Dynamic Modelling

31. What does the letter ‘p’ denote in the Vehicle Fixed Coordinate System according to SAE conventions?
a) Roll velocity of the vehicle about the x-axis or the forward direction
b) Roll velocity of the vehicle about the y-axis or the lateral direction
c) Pitch velocity of the vehicle about the x-axis or the forward direction
d) Pitch velocity of the vehicle about the y-axis or the lateral direction

Explanation: Roll velocity about the x-axis is given by the letter ‘p’ according to the SAE convention. The motion is called rolling which occurs in cases such as negotiating a turn. Pitch velocity of the vehicle about the y-axis or the lateral direction is given by the letter ‘q’ according to the SAE convention. The motion is called pitching and it occurs when a vehicle encounters a bump.

32. Which of the following can be the part of the sprung mass of the vehicle?
a) Knuckle
b) Hub
c) Wheel Assembly
d) Frame

Explanation: The frame of the vehicle is supported by the suspension subsystem which comprises of spring and dampers, hence it is a part sprung mass. On the other hand, knuckle, hub and the wheel assembly all comprise of the un-sprung mass as they are not supported by the suspension.

33. S.I unit of pitch velocity is ______
a) degree per second
c) rotation per minute
d) rotation per second

Explanation: Pitch velocity is the angular velocity of the vehicle about the y-axis. The S.I unit of angular velocity is radian per second.

34. Normal force acts along the z-direction.
a) True
b) False

Explanation: Normal force acts on the road. It acts in the vertical or z-direction according to the Vehicle Fixed Coordinate System.

35. The distributed mass system is used for most vehicle dynamic analyses.
a) True
b) False

Explanation: A lumped mass system is used for most vehicle dynamic analyses where the vehicle is assumed to be a single mass. A distributed mass system is more complicated and computationally expensive.

36. What kind of coordinate system is used as the Vehicle Fixed Coordinate System?
a) Left-hand orthogonal coordinate system
b) Cylindrical-coordinate system
c) Right-hand orthogonal coordinate system
d) Spherical Coordinate system

Explanation: In the right-hand orthogonal coordinate system, the x-axis represents the forward direction, the y-axis represents the lateral direction from the right of the vehicle and the z-axis represents the downward direction with respect to the vehicle. The cylindrical and spherical coordinate systems cannot be used to define the motion of road vehicles. The left-hand orthogonal coordinate system is often used to represent Fleming’s left-hand rule.

37. Vehicle velocities are normally referenced to the _____
a) Earth Fixed Coordinate System
b) Vehicle Fixed Coordinate System
c) Wheel Coordinate System
d) Engine Coordinate System

Explanation: Earth Fixed Coordinate System is used to define the vehicle trajectory and velocity during a maneuver. The vehicle motion is defined by the Vehicle Fixed Coordinate System. It involves forward, lateral, vertical, roll, pitch and yaw motions.

38. What angles define the relationship between the Vehicle Fixed Coordinate System and Earth Fixed Coordinate System?
a) Course angles
b) Trajectory angles
c) Delta angles
d) Euler angles

Explanation: Euler angles are defined by three rotation sequences. Keeping the earth system as a reference, the axis system is rotated in yaw first (about the z-axis), then pitch (about the y-axis) and then followed by rotating in roll (about the x-axis), to align it with the Vehicle Fixed Coordinate System. The respective angles obtained are called Euler angles.

39. In the schematic diagram given below, if ‘B’ represents the suspension system then what does ‘C’ represent?

a) Sprung mass
b) Free mass
c) Un-sprung mass
d) Constrained mass

Explanation: ‘C’ represents the wheel assembly which is not supported by the suspension ‘B’, hence it represents un-sprung mass. ‘A’ represents the sprung mass as it is supported by the suspension system.

40. Which force among the following forces acts in the longitudinal direction (x-axis) of a vehicle according to the Vehicle Fixed Coordinate System?
a) Reactive forces
b) Tractive forces
c) Gravity
d) Centrifugal force

Explanation: Tractive force is what drives the car in the forward direction. It is generated between the tire and the road and acts in the positive x-direction. Reactive forces are generated where the tire touches the ground. They act on the vehicle from the road in the negative z-direction or upward direction. Gravity acts on the center of gravity of the vehicle in the negative z-direction or downwards. Centrifugal force acts in the lateral direction along the y-axis.

More MCQs on Vehicle Dynamics:

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