4 ms·
~25mph assuming a Cd of 2.1 (a smooth brick is the closest I could find) a mass of 0.194Kg and a surface area of 0.01142313m^2 (75.6mm x 150.9mm). Of course th
by sbuk 3y ago
~25mph assuming a Cd of 2.1 (a smooth brick is the closest I could find) a mass of 0.194Kg and a surface area of 0.01142313m^2 (75.6mm x 150.9mm).
Of course that assumes it’s falling facing its largest surface, and not tumbling or a falling edge first. Obviously that is trickier to calculate, but 20-40mph doesn’t seem that unreasonable.
Edit: it takes ~3 seconds to reach 99% terminal velocity.
- xxs 3y agoThis feels like calculating a "spherical horse in a vacuum", except with drag this time.
- sbuk 3y agoFirst Monday morning back email avoidance tactics ;)
- peterleiser 3y agoHah, yeah. But it's a good problem solving and reasoning exercise. One of my courses in college used this book and it's very useful for reasoning about general real-world science topics: https://uscibooks.aip.org/books/consider-a-spherical-cow-a-course-in-environmental-problem-solving/ https://uscibooks.aip.org/books/consider-a-spherical-cow-a-c...
- robertlagrant 3y ago> Of course that assumes it’s falling facing its largest surface That was what I was thinking: surely it wouldn't be stable falling face-first? Wouldn't it be more likely to either tumble or settle on an edge?
- cesarb 3y ago> Wouldn't it be more likely to either tumble or settle on an edge? There's also the possibility that it behaves more like an airfoil, and starts generating lift once it's going fast enough.