Original post here. A BMW motorcycle is used to pull the tablecloth from under a banquet table with full formal setting. Go back and watch the videoclip.
Mythbusters story web clips: Tablecloth Chaos.
Executive Summary: Jamie was able to clear the tablecloth from under the banquet table setting. But only when he was able to get his custom bike to high speed before pulling the tablecloth. This required that the bike accelerate a distance with considerable slack in the rope.
The trick, as performed in the BMW ad, is not physics-ly possible. You simply cannot start from rest and jump to cloth-pulling speed on a motorcycle.
Shame on you, BMW.
Hat tip to Dan Burns via the AP Physics EDG.
The second video (the successful one) is kind of neat -- look at the exit sign. Is that a 60Hz flicker in slow motion? Makes for a nice timer for kinetics calculations if it is...
ReplyDeleteNow I don't think it has to be "shame on you BMW." Advertising is, by its nature, to be questioned. This "cool" demonstration inevitably will raise the statements "That's not possible," and "Yes it is, I remember my physics teacher doing something like that." If folks want to discuss whether this large of a tablecloth trick is possible, it will raise many good physics questions in the realm of friction, inertia, acceleration, etc. I would suggest that any teacher who does the tablecloth trick in class should follow it up with the BMW ad and ask if students think that would be possible.
ReplyDeleteAgreed. I would save it for a re-examination of the tablecloth trick (typically done in conjunction with Newton I instruction) after impulse has been taught.
ReplyDeleteI'm still unhappy with BMW for presenting a plausible but faked physics demo to make their product appear more capable than it could physics-ly be.