Vehicle Dynamics & Powertrain Flashcards
7 cards from real CAE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Vehicle Dynamics & Powertrain flashcards as text
What is 'brake fade' and what is its primary cause in drum or disc brake systems?
Answer: Reduction in braking force due to heat-induced decrease in friction coefficient
Brake fade occurs when sustained heat reduces the friction material's coefficient of friction, requiring greater pedal force to achieve the same deceleration.
How does a vehicle's polar moment of inertia affect its transient handling response?
Answer: Higher polar moment makes the vehicle slower to yaw, reducing agility but improving stability
A high polar moment (mass concentrated at the extremities) resists yaw changes, making the car feel more stable but less nimble in direction changes.
In engine mapping, what is a 'BSFC map' used for?
Answer: Identifying engine operating points that minimize fuel consumption per unit of power output
A Brake Specific Fuel Consumption (BSFC) map plots fuel mass per unit energy output across the engine's speed-load range to identify the most efficient operating zones.
What is 'dynamic weight transfer' and how does it affect tire loads during acceleration?
Answer: The shift of vertical tire load from front to rear axle as inertia acts on the vehicle's center of mass during acceleration
During acceleration, inertia acts at the CG height, creating a moment that unloads the front axle and increases rear axle load.
Which parameter most directly determines the natural frequency of a vehicle's suspension in bounce (heave)?
Answer: Spring rate and sprung mass at that corner
The natural frequency in heave is proportional to the square root of (spring rate / sprung mass), so both directly control ride frequency.
What is the function of a 'traction control system' (TCS) distinct from an anti-lock brake system (ABS)?
Answer: TCS prevents driven wheel spin during acceleration by reducing engine torque or applying brakes; ABS prevents wheel lockup during braking
TCS prevents excessive wheel spin during acceleration by reducing throttle or selectively braking spinning wheels, while ABS prevents wheel lockup during deceleration.
A turbocharged engine exhibits 'turbo lag.' What engineering solution does a twin-scroll turbocharger address this with?
Answer: Separating exhaust pulses into two scrolls to preserve pulse energy and spool the turbine faster
A twin-scroll turbo divides exhaust flow from cylinder pairs to prevent pulse interference and maintain pulse energy, improving spool response and reducing lag.