You are a professional witness in a lawsuit. What do youtell the judge? (Read th
ID: 1754760 • Letter: Y
Question
You are a professional witness in a lawsuit. What do youtell
the judge? (Read the following scenario.)
You are on an RTD Stretch Bus (the long busses with theaccordion in
the middle. (This is called an articulating bus.)) The bus isfully
loaded with fuel and people. You are traveling at 30 [mph] whena
mini-Van in front of the bus pulls in front of the bus as ittravels in
a similar direction; the van is traveling 20 [mph]. The busdriver slams
on the brakes, but there is black ice so the bus gracefullyslides
right into the van sending the van flying ahead. Threepassengers,
upon realizing their opportunity to make some quick cash, startcrying
of back and neck pain.
Mass of bus + passengers + fuel is about 66,600 [lb] or 30,200[kg].
Mass of van is about 2,000 [kg].
Forensics estimates from the bending of the light-pole that thevan was
moving at an uninhibited speed of about 35 [mph] when it hit thepole
after sliding on ice.
You are a professional witness; what is your statement to thejudge
and why? (Three other passengers tell the judge they didn't evenfeel
the collision. They heard it and saw the van fly forward; butthey
claim they felt nothing.)
I called RTD and spoke with a trainer.
He told me the Articulator holds 163 passengers, 183 gallons offuel
and weighs in at 66,600[lb] when fully loaded.
I also found some bus stats here:
http://www.rtd-denver.com/Projects/Criteria/index.html
http://www2.rtd-denver.com/Criteria/Bus/SECTION%2002%20-%20BUS%20FACILITY%20DESIGN.pdf
(Find page 9 and the "articulated" column.)
I was on a bus when this happened. We were traveling westward onEast
Colfax just west of Peoria Street. The van flew ahead of usand
crashed through a bunch of fence posts. People on the bus didmake
claims that they were seriously injured.
Explanation / Answer
Converting Miles Per Hours to Meters Per Second
30 mph = 13 m/s
20 mph = 8.9 m/s
35 mph = 16 m/s
Initial Momentum = 30200 kg * 13 m/s + 2000 kg * 8.9 m/s = 392600kg*m/s + 17800 kg*m/s = 410400 kg*m/s
Final Momentum of Van = 16 m/s * 2000 kg = 32000 kg*m/s
Final Momentum of Bus = 410400 kg*m/s - 32000 kg*m/s = 378400kg*m/s
Impulse = Change in Momentum = 32000 kg*m/s
Impulse = Mass * Change in Velocity = 32000 kg*m/s
Mass = 30200 kg
Change in Velocity = 1.06 m/s
The impact time is small causing on a small force on thehumans and this force would not cause injury to thepassengers.
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