The Projectile IncidentI was working in my study. Eli 13.7 was practicing the diabolo in the living room, and I heard the steady whir as it spun.
Then I heard a bang, or something.
Eli walked in a few seconds later. "Dad, I think the lawn guys just broke our door," he said.
"What?" I asked.
"Come look," he said.
There are about a thousand services in Austin that mow lawns, and we use one. They come by every two weeks in a big riding lawn mower.
We reached the entryway and Eli pointed (bottom right of the glass):
"You're right," I said. "Let's find what came through the glass." We looked around for a few seconds and saw a rock. This rock:
That's Gloria's hand, by the way.
The rock had only stopped when it hit a wall. That got my attention.
Here are the numbers, even though I've long forgotten how to calculate the speed of the projectile (I bet a bunch of you haven't, though):
Approximate distance from door when rock was ejected from mower: 25 feet.
Approximate mower blade RPM: 3,500
Rock height when it hit door: 26"
Rock height when it hit wall: 21"
Distance from door to wall: 15'
I don't know the exact speed, but that rock was moving.
The lawn service had the glass panel replaced in one day. Impressive.