If you triple your speed, stopping distance increases by?

If you triple your speed, stopping distance increases by?

• A. Three times
• B. Six times
• C. Twelve times
• D. Nine times

Answer: (D)

Stopping distance grows with the square of your speed. The braking distance, which dominates stopping distance under constant braking, is proportional to v^2. So if you triple your speed, the braking distance becomes 3^2 = 9 times longer. Therefore, the stopping distance increases by nine times. In real driving, reaction distance (which increases linearly with speed) would add a bit more, but the key idea here is that braking distance scales with speed squared, giving nine times when speed is tripled.

Stopping distance grows with the square of your speed. The braking distance, which dominates stopping distance under constant braking, is proportional to v^2. So if you triple your speed, the braking distance becomes 3^2 = 9 times longer. Therefore, the stopping distance increases by nine times. In real driving, reaction distance (which increases linearly with speed) would add a bit more, but the key idea here is that braking distance scales with speed squared, giving nine times when speed is tripled.