AK Dad
New member
So, being a relatively new Tech I hadn't spent much time with the 2011 LATCH Manual until someone gave me a copy about 2 months ago (likely because it's now outdated.) I still enjoyed reading it right up until I got to P.16 where it says in reference to CR sled tests:
That is a huge misunderstanding of Newtonian physics!!! Not just a bit wrong, but wrong by a factor of 4 (since kinetic energy goes up as the square of velocity). It is however equivalent to two vehicles of equal mass, one stationary and the other going 60 mph, or, even simpler, two vehicles of equal mass hitting head-on at 30 mph.
Anyway, I didn't worry about it too much because I figured some physics nerd (like me) would have noticed that and let them know before they released the 2013 revision. BUT NO! I just got my new 2013 edition in the mail and the same error is right there on P.82 again!
Am I too annoyed by this? Maybe. Even the Mythbusters screwed this up a while back, but they got so much crap for it from the fans that they went back and did an entire show about it. Here's a 5 minute excerpt that beautifully illustrates this with absolutely (well, almost) no math involved.
[ame="http://www.youtube.com/watch?v=r8E5dUnLmh4"]Mythbusters - Car crash force - YouTube[/ame]
OK, so why do I care that one sentence in a 200+ page book is wrong? Well, it makes me concerned that when they give an opinion on other matters they could also be off by a factor of 4. (I'm probably making too big a deal of it though.)
Anyway, that is all ... now hopefully I can go to bed and get to sleep ...
This is a very severe test, equal to hitting a solid wall at 30 mph or two vehicles of equal size hitting each other head-on at 60 mph.
That is a huge misunderstanding of Newtonian physics!!! Not just a bit wrong, but wrong by a factor of 4 (since kinetic energy goes up as the square of velocity). It is however equivalent to two vehicles of equal mass, one stationary and the other going 60 mph, or, even simpler, two vehicles of equal mass hitting head-on at 30 mph.
Anyway, I didn't worry about it too much because I figured some physics nerd (like me) would have noticed that and let them know before they released the 2013 revision. BUT NO! I just got my new 2013 edition in the mail and the same error is right there on P.82 again!
Am I too annoyed by this? Maybe. Even the Mythbusters screwed this up a while back, but they got so much crap for it from the fans that they went back and did an entire show about it. Here's a 5 minute excerpt that beautifully illustrates this with absolutely (well, almost) no math involved.
[ame="http://www.youtube.com/watch?v=r8E5dUnLmh4"]Mythbusters - Car crash force - YouTube[/ame]
OK, so why do I care that one sentence in a 200+ page book is wrong? Well, it makes me concerned that when they give an opinion on other matters they could also be off by a factor of 4. (I'm probably making too big a deal of it though.)
Anyway, that is all ... now hopefully I can go to bed and get to sleep ...
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