If one vehicle is going 20 mph and another is going 60 mph, the faster vehicle has how many times the force at impact compared to the slower vehicle?

• A. 3
• B. 9
• C. 2
• D. 6

Answer: (B)

In a crash, if the stopping distance is the same and the masses are similar, the force you need to stop a vehicle grows with the square of its speed. That means the ratio of forces is (60/20) squared. Since 60 mph is three times faster than 20 mph, the force increases by 3^2, which is 9. So the faster vehicle experiences nine times the impact force. This relies on the same stopping distance (crumple zone) and similar mass; if those change, the numbers would shift, but the squared-speed relationship under a fixed stopping distance is the standard takeaway.