Depends upon how squishy the roof/substrate is. The acceleration-to-height or compressive stress-to-height conversion is not well-defined in general. If you're

Depends upon how squishy the roof/substrate is. The acceleration-to-height or compressive stress-to-height conversion is not well-defined in general. If you're optimizing for dropping a car on its roof from a specified height, it's probably better to drop the car on its roof.