If a driver doubles their vehicle's speed from 30\text{ mph} to 60\text{ mph}, the braking… — DMV Permit Practice Test

If a driver doubles their vehicle's speed from $30\text{ mph}$ to $60\text{ mph}$ , the braking distance required to bring the vehicle to a complete stop increases by four times.

Answer: Answer

Answer

True

The statement is true because a vehicle's kinetic energy increases with the square of its speed. Consequently, doubling the driving speed increases the required braking distance by a factor of four.

Step-by-Step Solution

Identify the physical relationship between vehicle speed and braking distance.

Braking distance increases proportionally to the square of speed (

v^2

A vehicle's kinetic energy depends on speed squared (

E_k = \frac{1}{2}m v^2

), and friction must do work over a distance to dissipate this energy.

Calculate the factor change in braking distance when speed is doubled.

Multiplying speed by

2

multiplies kinetic energy and braking distance by

2^2 = 4

Doubling vehicle speed results in four times the braking distance.

Key Concept

Kinetic energy and braking distance relationship

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