Eeeek! Commiserations on both connections and falling bookcases.

You've got to watch the latter. One of them took out composer Charles-Valentin Alkan a century or so ago . . .

I believe that the bookshelf would be one of those nice little physics problems where everything depends entirely on the height fallen, so v=sqrt(2hg) v being velocity, h being the height fallen and g being gravitational acceleration. My computer's calculator says something in the are of 4.44 meters/second. or just under 10 miles per hour. now if you wanted us to calculate the force which which it hit you, that's a little trickier.

Well, assume a spherical bookcase of uniform density. We'd assume a spherical fan of uniform density, but I'm not the one getting hit.

Things we need to know.

1) How high was your shoulder at impact?

2) Mass of the bookshelf?

3) Angle of the bookshelf, relative to the floor, when it impacted (part of the shelf's mass will be supported by the floor.)

4) Do you have a phone line you can give up for a couple of days? You could just dial in 24-7, and route the network that way.

Sympathies on the back. My shoulders are starting to niggle at me, but at least the dr gave me good exercises to maybe help the knees. You know, those falling bookcases can be quite dangerous, especially if they're full of books which, thank ghu and roscoe, this one wasn't. Was your phone reachable if it had done real damage? When pursuing dangerous activities while home alone it is wise to keep at least the cellphone handy. Says the woman who fell down the stairs while home alone. It's really amazing how fast the brain can move. Between realizing I wasn't going to get my balance back and actually hitting the floor I had time to think, "Oh my god I'm going to fall. Oh my god I'm home by myself. Oh my god, if I break something I can't reach a phone." Fortunately I didn't break anything though it didn't do my back any good at all. Hope yours is less damaged or at least that you have a good chiropractor. This is the kind of thing they're good at.

MKK

I hope you're feeling better. Never had a bookcase fall on me. I have had trees narrowly miss, though....

I had a bookcase fall on me once, but it was when I was a teenager and making out with my boyfriend and we knocked it over. (I still don't know how. We weren't being that vigorous. I think it involved leaning just wrong, or something.) Boy, were my parents pissed, though. We managed to knock over the bookcase with the fragile, 140 year old books in it, of course. *wince*

For a fall of that distance, the bookcase would probably be moving somewhere in the neighborhood of 5 m/s (for reference, a brisk, "I'm late for a con panel" walk is about 2 m/s). There are two different ways to figure it (as a straight drop, or as a rectangular object rotating about its bottm end), which give slightly different results (4.6 and 5.6 m/s, respectively), but both use conservation of energy, and are independent of the mass of the bookcase.

I had one fall over at me once (I caught it and was only showered with books). Since then I shim them so that they lean against the wall, no matter how much weight is put in them. Of course, it still takes only one moron/child trying to climb them to pull them down, or a neutronium clip on the front.

Fortunately, morons don't get to come to my house, I watch children hawkishly when they do, and I haven't seen one of those little neutronium clips in years.

Much commiseration on both fronts. When our DSL went out for an afternoon (while they were switching us to cable) it felt like being stuck in molasses.

Never had a bookcase fall on me, but our cat once knocked me off a ladder while I was cutting in around the ceiling. The funny thing about that (now--it didn't seem so at the time) was the flurry of little wallcolor-white kittyprints *all over* the apartment that I got to clean up. He had quite a stride when he was spooked!

The falling-bookcase problem is more complicated than it first might seem at first glance. It's a rotating object, rotating about a fixed point on the floor. At the point of impact its rotational kinetic energy should equal its change of gravitational potential energy.

I work out that the top of the bookcase is moving at something like 2.3 meters per second (7.5 feet per second)if I assume that the bookcase's mass is uniformly distributed along its height. (This won't actually be the case, as there will be lumps of mass at the level of its shelves.)

How much does the bookshelf weigh, about?

What's it made out of, how much, and so on?

Can you attach a photo?

Erik asks:

Things we need to know.

1) How high was your shoulder at impact?

From the statement of the problem: elev. 54.2594

2) Mass of the bookshelf?

Unknown, awaiting clarification.

3) Angle of the bookshelf, relative to the floor, when it impacted (part of the shelf's mass will be supported by the floor.)

We know the height of the bookshelf (8', or 96"), and the height of the shoulder is 54.25". This means she was standing 79" (6' 7") from the base of the bookshelf, and the angle of the bookshelf from the floor at the time of impact was approximately 250.

1) How high was your shoulder at impact?

From the statement of the problem: elev. 54.2594

No. I took that as normal baseline elevation of the shoulder. I'm assuming at least some effort was made to avoid the bookshelf, which could have changed that elevation. (which is why I qualified with "at impact.")

Was she ducking? Running? Turning to run, which might have elevated a shoulder? Trying to hold the shelf back, which would have elevated the shoulder?

Bad bookcase! Bad! Down! No, I mean up...!

(This was a very young bookcase, and still rambunctious. Ritalin in the varnish would probably have helped.)

Ah, the hazards of biliophilia! (Feel better.)

I got the opportunity to do some cursing of my own late this afternoon when I discovered that my web host, your-site.com, had had server problems and restored service with 6 week old versions of my files. They swear the current ones will be back by late Sunday. But I was really getting going on my blog and hadn't taken the time to back up this week.

So while we're damning ISPs, I'd like to add your-site.com to the collection. Their service is cheap and I'm in the process of getting what I paid for.

It's actually a good idea to fasten 'cases to the wall, neutronium clips notwithstanding. Of course, I live in earthquake country...

Sympathies, here.

Ouch! Best wishes for speedy recovery. Should I take it that Patrick's laptop is the only equipment with a dial-up modem to account for your limitation of access?

We're achy up here, though it's our own fault. If you check Nancy's blog (Windhaven Exhalations on Patrick's friends list) there are a few photos of some of the demolition at our place. Yesterday the old garden shed went the way of all shoddily constructed outbuildings. So did the frame of the above-ground pool that came with the place. Sadly, so has a lot of the garden. Many changes still to come. Wish us luck with the zoning board next month.

My sympathies, Teresa. I'll refrain from physicing, both from the fact that I don't know squat, and from good taste :)

Ow-ow-ow on all accounts. The Mother of the World sends soft chicken soup and hot sweaters. Or is it the other way around? The Mother of the World is getting old and foggy.

Jane

Teresa - make sure you get medical attention now. Back injuries may take several weeks to fully develop into their full slipped-disc sciatic awfulness; and, once they do, you'll be seeing physical therapists for years. In my case, what I thought was a simple fall down the stairs (while moving furniture) became a nightmare with episodes of immense pain. Screaming in the HMO office helps get you past their "just take aspirin" stage, too.

Teresa--My sympathies--I've had my share of back problems, and of falling bookcases, but never together. (The bookcase in the alcove next to my bathroom, which had stood quite peacefully where it was for 14 years or so, fell while I was out one evening. Since the alcove is only about 4 ft wide, the bookcase remained tilted at about 60 degrees, but emptied its contents into a heap on the floor, blocking access to the bathroom. This was not fun when I arrived home a bit on the tipsy side and had to stack everything up everywhere before I could get to the bathroom...
I hpe you put ice on your shoulder....

Exactly 27.3 mph. Exactly.

Bee Raneak, would you care to explain how you calculated your answer? It looks way too big to me.

OUCH!

We do expect color photos of the bruises as they progress to that unique green.

Was the bookcase one of those pressed wood ones? They are much heavier than real wood. Still, bookcases must be installed.

I am really sorry.

Alan, how can you doubt an answer computed by an alien android?

Could be worse.

Hope you feel better.

Ah, but Teresa doesn't weigh anything like 120 kilos, which the man in your example did. It wouldn't take much to fasten him to the floor: in the last years of his life, Kingsley Amis grew so fat that he would regularly get stuck when he fell over and bang on the floor so that his first wife, her third husband, or both, could come up from the flat below and haul him to his feet.

Lo, how I suffer. I am irritated! I am indignant! Woe!

My sympathies - connection and back-wise. SBC/PacBell finally restored my phone service today ... it's been out since last Tuesday. Why? Who knows - they sure didn't, it took them four days just to send a repairman, and two more days after that before a second repairman came by to actually fix the problem.

No phone, no DSL, no ... anything.

My father, who had three very inquisitive sons in the house, used to screw bookcases in the wall at the top. To make one fall over, one of us little darlings had to physically rip it out of a solid brick wall. He normally used 1 inch screws and rawlplugs (I have no idea what you'd call them in America: You drill a hole in the wall, put in a plastic thing and screw the screw into the plastic thing. The plastic thing is the Rawlplug, which is a brandname.)

By the time we were strong enough to rip the bookcases out, we all had well established reading habits and preferred our bookcases to be upright, thankyewverymuch.

dave

Not going to attempt the bookcase problem, as I am post-festival sleep deprived, and there are better mathemagical minds than mine here. I do hope that you get connected to the world again, and that your back is merely bruised and not wrenched, sprained, slipped, or otherwise seriously damaged.

Rest, ibuprofin (if you don't react poorly to it), tea, and heat are the preferred post-bike tumble treatments here, I think they might work as well for bookshelf injuries.

dave:

What you call Rawlplugs are called screw anchors in the USA.