SCIENCE & CULTURE CORNER
Buckle Your Seat Belt
Routinely planes recommend, but do not require seatbelts be attached. Can you infer from this that it is safe to leave them unbuckled? Why do some passengers keep buckled up while others don't?
Most of us have experienced how we are forced forward or backward when a train we are riding changes speed. We also know that should a moving automobile crash, the front seat passengers (if without seat belts or air bags) may continue traveling right through the windshield. This is the force of inertia recognized by Newton. Simply put: objects moving tend to continue moving in the same direction and at the same speed. Stationary objects tend to remain stationary as well.
Further, the amount of force involved is the weight (actually mass) of the object times the square of its speed. Thus a 1-ton truck travelling at 100 kilometers per hour would hit a stone wall with much greater force than a 2-ton truck travelling at 50kph. Since planes travel much faster than automobiles, the force of inertia is much greater.
Yet, it is not just a crash, or the slight chance of being sucked out a hole in the side. The most likely danger is air turbulence. Should the plane unexpectedly drop 20 meters, Newton's inertia would have you at the same altitude, i.e. above the plane. The real effect of this would be to crash you hard into the ceiling.
There is little you can do about dinners and drinks jumping around when turbulence hits. Nor can you keep the belt on when walking to the rest room. But if next time you fly you inquire as to whom around you is an engineer or a science teacher, you'll see they are the ones with their belts always buckled. That ought to tell you something.
by Angel
Stephens
angel_stephens@hotmail.com
Angel Stephens received his degree in social science from Harvard and writes on physical science and anthropology for a number of publications. He lives in the US and may be contacted at angel_stephens@hotmail.com
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