In response to a question asked on the Car Talk radio program, Rhett Allain does the math to find out if falling bird poop can crack a windshield.
The answer: maybe. There are just a lot of assumptions that have to be made. Is falling bird poop spherical? What’s its density? How does the bird poop deform on impact? What is the compressive strength of automobile glass?
This is however an excellent real-life application of back-of-the-envelope physics and algebra. It required calculating:
- the volume of the poop – extrapolated from the diameter of the residue on the windshield;
- the terminal velocity of the poop – the velocity where gravity’s force is exactly counterbalanced by wind resistance so the poop is at its maximum speed;
- the force of impact – calculated using the work done as the poop splatters;
- and the pressure imparted by that force.
