A vehicle that is twice the weight of a car and is travelling at twice the speed of that car requires how much braking power to stop in the same distance?
- Six times as much
- Twice as much
- Four times as much
- Eight times as much ✓
Answer: D. Eight times as much
Eight times as much braking power is required when a vehicle is twice the weight of a car and travelling at twice its speed.
Why this is the answer
The handbook's speed and weight facts say that doubling vehicle speed alone calls for four times the stopping power, and doubling vehicle weight alone calls for twice the stopping power. When both happen together, the requirement is eight times the stopping power. That matches the situation in the question: twice the car's weight and twice its speed.
Why the other answers are wrong
- A. Six times as much — Six times as much is not supported, because the handbook gives eight times when both speed and weight are doubled.
- B. Twice as much — Twice as much accounts only for the doubled weight and leaves out the effect of the doubled speed.
- C. Four times as much — Four times as much accounts only for the doubled speed and leaves out the effect of the doubled weight.
Remember it
Double the speed and double the weight together, and the braking power needed climbs to eight times.