If you double both your vehicle's weight and speed, by how much will the stopping distance increase?
- Two times
- Eight times ✓
- Six times
- Four times
Answer: B. Eight times
Doubling both weight and speed increases stopping distance by eight times.
Why this is the answer
The handbook treats the two effects separately and then combines them. Doubling speed makes stopping distance four times longer, while doubling weight makes it twice as long. Applying both changes together multiplies those effects, so the stopping distance becomes eight times greater. That is why the answer is eight times, not simply twice or four times.
Why the other answers are wrong
- A. Two times — Two times only accounts for doubling the weight; it ignores the separate effect of doubling speed.
- C. Six times — Six times is not produced by combining the handbook's two effects: double speed gives four times and double weight gives two times.
- D. Four times — Four times is only the speed effect; it does not include the extra doubling from the heavier vehicle.
Remember it
Remember it as speed first: double speed, four times the distance; then add double weight for eight.