Last year, our son-in-law, Ian, fell when the ladder he was using collapsed out from under him. Given that his head had been more or less at the same level as the eaves of their single story house, it had accelerated to approximately 13 feet per second when it hit the cement patio. Unsurprisingly, the impact knocked him out. Thankfully, all he suffered was a severe concussion. It could have been much worse.
From our backyard, I have been watching a Northern Flicker make a hole in the mostly-dead oak tree next door. According to one website, the woodpecker’s beak is hitting that trunk at a significantly higher speed than Ian’s head was going when it hit the pavement—closer to 19 feet per second.