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plutherusToday's math problem:
I have a bookshelf, it weighs 140 pounds, empty, and is 6 feet tall.
After assembling it, with one end resting on the ground, I lifted the other end to make about a 45 degree angle.
Then the top broke, and it fell. Both my hands were still underneath it. Because of the small amount of room, I could not step back or lean down, or even squat, so my arms caught the full force of it falling, at about 30 degrees. It dropped about 2 more degrees before coming to a rest, at which point I was finally able to maneuver to the point where I could set it down.
So, given that the downward acceleration vector is 9.8m/s^2 (because we're on Earth), how fast was it going at the time it impacted my hands? At 30 degrees to the horizontal, how much of the mass was resisted by my hands? Changing the velocity from that calculated to zero within two degrees of motion resulted in how much force?
Yeah, that's how much force came crashing down on both my arms, severely pulling my biceps and forearm muscles, causing enough pain that all I could do was stumble out of the room and fall down moaning in the hall for several moments.
Fortunately, due to all the aikido lately, I've reached the point where I can actually stand back up without using my hands. And fortunately, C, also thanks to the aikido, has lots of experience with pulled muscles. So we had on hand ibuprofen and Zheng Gu Shui, which is a wonderful ointment found in the Asian store (and, I would guess, other places).
So, getting better, no trip to the emergency room required this time.
Over the last four hours, the pain has subsided enough that I can now type.
But not enough that I can sleep for more than a few minutes.
And I've got a book, Musashi by Eiji Yoshikawa, sitting on my night stand, taunting me. I want to read it, but it's a large hardback book, and it's still too painful to lift it up. Bet that wouldn't have stopped him, though :P
I have a bookshelf, it weighs 140 pounds, empty, and is 6 feet tall.
After assembling it, with one end resting on the ground, I lifted the other end to make about a 45 degree angle.
Then the top broke, and it fell. Both my hands were still underneath it. Because of the small amount of room, I could not step back or lean down, or even squat, so my arms caught the full force of it falling, at about 30 degrees. It dropped about 2 more degrees before coming to a rest, at which point I was finally able to maneuver to the point where I could set it down.
So, given that the downward acceleration vector is 9.8m/s^2 (because we're on Earth), how fast was it going at the time it impacted my hands? At 30 degrees to the horizontal, how much of the mass was resisted by my hands? Changing the velocity from that calculated to zero within two degrees of motion resulted in how much force?
Yeah, that's how much force came crashing down on both my arms, severely pulling my biceps and forearm muscles, causing enough pain that all I could do was stumble out of the room and fall down moaning in the hall for several moments.
Fortunately, due to all the aikido lately, I've reached the point where I can actually stand back up without using my hands. And fortunately, C, also thanks to the aikido, has lots of experience with pulled muscles. So we had on hand ibuprofen and Zheng Gu Shui, which is a wonderful ointment found in the Asian store (and, I would guess, other places).
So, getting better, no trip to the emergency room required this time.
Over the last four hours, the pain has subsided enough that I can now type.
But not enough that I can sleep for more than a few minutes.
And I've got a book, Musashi by Eiji Yoshikawa, sitting on my night stand, taunting me. I want to read it, but it's a large hardback book, and it's still too painful to lift it up. Bet that wouldn't have stopped him, though :P
