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A
The brakes are failing
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B
Forward liquid surge — the liquid continues moving toward the front of the tank when brakes are applied, creating a brief forward momentum that counteracts braking; this is the characteristic surge effect that makes tankers harder to stop than equivalent solid-load vehicles
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C
The engine is over-revving
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D
The tires are overinflated
Why this is the answer
FORWARD SURGE AT BRAKING is one of the most important and most tested tanker driving concepts. PHYSICS EXPLANATION: When you apply the brakes, the vehicle structure (axles, frame, cab) begins to decelerate. The liquid inside the tank, following Newton's First Law, continues at its current speed — it has inertia. The forward-moving liquid effectively 'pushes' the vehicle forward, partially counteracting the braking force. The result is: braking feels less effective initially; the vehicle travels further before stopping than a solid-load truck of equivalent weight; the 'push through' sensation is felt by the driver as reduced brake effectiveness; after the liquid wave reaches the front bulkhead and splashes back, the surge effect diminishes and normal deceleration resumes. CRITICAL IMPLICATION FOR STOPPING DISTANCE: A tanker cannot stop as quickly as a solid-load truck of the same weight. Test after test shows tankers require 10-30% more stopping distance depending on fill level, baffle design, and speed. Tanker drivers must internalize this and keep much greater following distances and begin braking much earlier than a standard CMV driver would. BAFFLES HELP — they slow but do not eliminate surge; an unbaffled smooth-bore tank has the most severe surge effect.
Source: FMCSA CDL Manual, Chapter 10, Tank Vehicles, Surge Effects on Braking