worley expo

8/2/2019 Worley Expo

1/4

The extreme conditions of a tornado can force a straw into a telephone pole. This is a common

phenomenon associated with the destructive force of this type of windstorm. The feat itself is based on

much conjecture, however the folks over at the National Oceanic and Atmospheric Administration say

that tornadoes are certainly strong enough to turn otherwise harmless items into deadly missiles

(http://www.ncdc.noaa.gov/oa/climate/severeweather/tornadosafety.html). This is demonstrated by

the images below:

A harmless record album became a disc of terror through the awe-inspiring forces contained within a

tornado.

A slat of wood was driven through a fairly thick palm tree during a storm with gale-force winds.

The dynamic forces within a tornado are complicated, but not entirely incapable of being re-produced in

a lab, as the masterminds behind Discovery Channels MythBusters demonstrated when they attempted


2/4

to put the straw through a telephone pole theory to the test. The results were semi-fantastic and

resulted in the straw pushing one-fourth of the way into a palm tree, at 320mph.

At Pie, we tried something a little lower-key, and had two of our forensic investigators Brad Stolz, P.E.

and Tyler Schwein, E.I.T. estimate the velocity needed for a Spyderco knife to pierce through a 2x4.

These calculations evolved and turned into a popular contest that was featured at the 2012 Worley Expoin Houston, Texas.

Although our investigation involved less panache than the MythBusters experiment, we created a

unique display for the Spyderco knife that i llustrated this phenomenon, and asked two very concise

questions:

1. What velocity (MPH) is required for the knife blade only to pass through this 2x4? (as you see inthe picture below)

2. Assuming the knife will completely penetrate (pass all the way through) the 2x4 at 122mph yesor no does the orientation of the knife matter? (Blade first or handle first?)

A local Texan guessed the speed, 77/mph, spot on (without doing any calculations), and was also

correct regarding the orientation of the knife. And the reward for the correct answer? The Spyderco

knife of course. We received a lot of great comments about the contest and many shared their own

stories regarding the amazing forces of tornadoes. All was well with the world once again.

Butwait; is there a viable explanation for how an object of small mass can penetrate another

object of greater mass? There certainly is!

Vince Calder on the Ask a Scientist portion of the NETWON website simplifies, saying, if I jump

into a lake from a height of 1 meter, I just sink and make a splash -- no harm. But if I jump into the

same lake from an airplane at 1000 meters above the surface, I'm a pancake. I might just as well hit

solid ground. The reason is: at the speed with which I hit the water is so fast, the water does not


3/4

have time to "get out of the way" so it becomes essentially a solid. This is what happens to straws

etc. driven by tornadic winds. (http://www.newton.dep.anl.gov/askasci/phy00/phy00325.htm).

Another interesting fact about these objects becoming lodged in things is that the object lodged is

usually intact, showing very little damage.

For example:

This question and numerous others are constantly being considered in the research for finding out how

tornadoes work and how to better predict them. If this can be accomplished in the near future, it is

hopeful that loss of life and property damage may be reduced.

In the meantime, you can rest assured Pie will keep providing forensic engineering expertise in

catastrophic situations, helping you solve complex challenges as you deal with insurance claims.


4/4

March 2, 2012 tornado destruction in Henryville, Indiana.

worley expo

Documents