 |
| The Gap, 188-. From the State Library of NSW |
Yesterday, after 3 years in gaol, Gordon Wood was acquitted of murder after he was originally found to have pushed his girlfriend, Caroline Byrne, off this popular suicide spot. In the original guilty verdict, the evidence relied on an expert witness called Rod Cross who subsequently wrote the book, "Evidence of Murder: How Physics Convicted a Killer." Previously, Cross had written books about the physics of tennis.
The physics of the Murder/Suicide/Misadventure is best found at mathspigs. In short, the cliff is 29m high and the body was found on the rock ledge below, 11.8m out from the cliff. This means the woman's velocity when she left the cliff was 4.85m/s. Since she couldn't have run off the cliff (there is a fence only 1.5m away from the edge), the woman was deemed to have been thrown off the edge and her partner went to gaol. Now this ruling has been overturned!
In the appeal, the judge ruled that to throw someone so far away from the edge of the cliff would endanger the life of the murderer. They figured this out by having some police officers throw others into a pool. Also, Gordon Wood was chaffeur for a famous rich man called Rene Rivkin. At the time of Byrne's death, Wood and Rivkin were being asked by the Australian Securities and Investment Commission (ASIC) about a suspicious fire and true ownership of shares in the company affected by the fire. In the murder appeal, the judge ruled the original jury should not have known about ASIC questioning Wood and Rivkin.
So, if she didn't run off the cliff, wasn't pushed, what now...?
Here is the trajectory of a body that mysteriously alighted from a cliff 29m high and landed 11.8m out from the base. Take the photo and use it with your class. CSI comes to maths!
 |
| Trajectory of a body that mysteriously alighted from a cliff 29m high and landed 11.8m out from the base. |
The equation of the parabola simplifies to:
y = - 5x2/24
If Byrne has taken her own life, she was running at 4.85m/s when she left the cliff. Could have Byrne reached the necessary velocity in 1.5m? This would require an acceleration of 7.84m/s2.
Let's try it. That means you need to run 1.5m in 0.62s. Can data loggers help us accurately measure our rate of acceleration?
You are actually wrong about the distance. It was not 1.5m. It was alleged to be 4m at trial because of the supposed presence of bush, but was subsequently discovered that a total run-up of 6m was available at the time of death as there was no bush present. I think you are getting confused with the 'original' take-off point which is where the viewing platform fence comes closest to the edge of the cliff, but the cliff is only 25m high there. A/P Cross decided that was not the correct take-off point and selected one further to the north which became known at the Northern Ledge. This was the take-off point referred to at trial and allows for a 6m run-off.
ReplyDelete