ASVAB Auto and Shop: Vehicle Braking, Cooling, and Electrical Systems — Questions and Answers
Question 1: Which principle explains how pressing the brake pedal transmits force through brake fluid to the wheel cylinders or calipers?
- Bernoulli's principle
- Pascal's law (Correct answer)
- Newton's third law
- Archimedes' principle
Correct answer: Pascal's law
Pascal's law states that pressure applied to a confined fluid is transmitted equally in all directions. Hydraulic braking systems use this principle: foot pressure on the pedal pressurizes brake fluid, which multiplies the force at each wheel.
Question 2: What is the primary function of the thermostat in a vehicle's cooling system?
- To pump coolant through the engine block
- To regulate coolant flow based on engine temperature (Correct answer)
- To remove heat from the coolant using airflow
- To pressurize the cooling system to raise the boiling point
Correct answer: To regulate coolant flow based on engine temperature
The thermostat is a temperature-sensitive valve that stays closed when the engine is cold (keeping coolant in the engine to warm up quickly) and opens when the engine reaches operating temperature to allow coolant to flow to the radiator.
Question 3: Which vehicle component converts mechanical energy from the engine into electrical energy to recharge the battery while the vehicle is running?
- Starter motor
- Voltage regulator
- Alternator (Correct answer)
- Distributor
Correct answer: Alternator
The alternator is a generator driven by the engine's serpentine belt. It produces AC electricity, which is converted to DC to charge the battery and power the vehicle's electrical systems while running.
Question 4: Disc brakes use which component to squeeze against the rotor and create stopping friction?
- Brake drum
- Brake shoe
- Brake caliper and pad (Correct answer)
- Wheel cylinder
Correct answer: Brake caliper and pad
In a disc brake system, the caliper clamps brake pads against both sides of the spinning rotor (disc). This friction slows wheel rotation. Drums and shoes are found in drum brake systems, not disc systems.
Question 5: What is the purpose of a vehicle's radiator?
- To filter contaminants from engine coolant
- To store excess coolant when the system is pressurized
- To transfer heat from the coolant to the surrounding air (Correct answer)
- To mix air and fuel before combustion
Correct answer: To transfer heat from the coolant to the surrounding air
The radiator is a heat exchanger. Hot coolant flows through its tubes while air passes over fins surrounding those tubes, removing heat from the coolant before it recirculates back into the engine.
Question 6: A vehicle's fuse blows repeatedly on the same circuit. What is most likely the root cause?
- The battery is discharged
- There is a short circuit or excessive current draw in that circuit (Correct answer)
- The alternator is overcharging the battery
- The coolant level is low
Correct answer: There is a short circuit or excessive current draw in that circuit
Fuses are protective devices that blow when current exceeds safe levels. Repeated fuse failure on the same circuit points to a short circuit (unintended path to ground) or a component drawing more current than the circuit is designed for — replacing the fuse without fixing the underlying fault is unsafe.
ASVAB Auto and Shop: Vehicle Braking, Cooling, and Electrical Systems
Which principle explains how pressing the brake pedal transmits force through brake fluid to the wheel cylinders or calipers?