Posted on 05/16/2015 3:52:39 PM PDT by Duke C.
Basic physics states that F+MV² ( force= mass times velocity squared)
Let's say a thug tosses a bowling ball at Amtrak 188, presently moving at 70 MPH.
That would be 15LBS times 88FPS which would equal 1,742,000 foot pounds of energy.
Don't know if this is right, my physics is rusty. Anybody?
Will a train going through that curve at 106 mph derail?
Let’s try it again.
Keep the Frogs off of the track./s
Well the tracks go through South Philly...
No, but pushing the train’s speed up to over one hundred MPH going into a fifty MPH curve can......
“That does not explain why this engineer was going 106 MPH in a 50 MPH
zone.”
What if the projectile was a diversion for a hacker to take control of the train? Why would it be any different from the hacker and the plane?
I could never understand why bicyclists would want a derailer. My chain comes off the front sprockets just fine all by itself.....
I read that a RR Engineer said there were multiple levers to advance in order to increase speed, not just one. SO this guy was so startled, he pushed them all forward at the same time? Heading into a curve he had to have known was coming?
Only if the brakes are full emergency on....
Ben Ghazi found them.
I dop not know, just reported on what some expert was saying on Fox news. He speculated on the possibility.
I may not have understood his explanation, but I thought he said there was only one lever.
Who knows... we will probably hear all kinds of speculation before this is over.
If these lever or levers are somewhat vertical I suppose it is possible the engineer slammed into them accidentally either panicked or literally hit with a flying object, but it would depend how the control boards are situated which I have no idea.
The simplest explanation is that train was cruising at 100 MPH
and the gay engineer did not slow the train before the curve.
It is reported that he slammed on the brakes before the crash.
Apparently he wasn’t that startled.
Your analogy is a good one. Also, hit a car with a rock that shatters the windshield, causing a wreck, while the driver is 20 MPH over the speed limit and see where fault is assessed.
You mean like a LEAD FOOT on the gas pedal?
Because that's the formula for kinetic energy. Mass time 1/2 the square of velocity.
“Let’s say a thug tosses a bowling ball at Amtrak 188, presently moving at 70 MPH. That would be 15LBS times 88FPS which would equal 1,742,000 foot pounds of energy.”
[Duke C’s initial approximation]
“The ball’s kinetic energy would be
0.5*15*(70*5280/3600)**2 = 79,053.3 foot-pounds
or about 0.0298 kilowatt-hours.”
[cynwoody’s approximation]
Neither used the correct amount for mass. In the English/American system of units, pounds are a measure of force, not mass.
f = ma (force equals mass times acceleration)
Inserting the actual figures, we get
15 pounds = m * 32.17 ft/sec**2 (gravitational acceleration at earth’s surface).
Solving for m, we find the mass of the bowling ball to be
m = f/a = 15/32.17 = 0.4663 pound-sec**2/ft (a unit commonly referred to as “slug” in engineering parlance)
Not sure where cynwoody found the conversion figure from mph to ft/sec but it is in error. The very first, most basic figure learned by aero engineers (and rocket scientists, and ballisticians) is 60 mph = 88 ft/sec (60 statute miles/hr = 316800 ft/hr / 3600 sec/hr = 88 ft/sec)
70 mph converts thus:
70 * 5280 ft/mile / 3600 sec/hr = 102.67 ft/sec
The equation to give us kinetic energy thus becomes
E = (0.4663 * (102.67)**2) / 2 = 2457 foot-pounds.
Not sure where cynwoody found the conversion figure from mph to ft/sec but it is in error.
Actually, that part of my calculation was dead on: (70 miles per hour * 5280 feet per mile / 3600 seconds per hour) = 102.7 feet per second (or 31.29 m/s).
Where I went wrong was in assuming the formula ke = 0.5*m*v**2 actually yielded foot-pounds. My next step was to ask Google, what is 79053.3 foot-pounds in kwh? Garbage in, garbage out, LOL!
If you instead take the bowling ball's mass in kilograms and the train's velocity in meters / second, the calculation is 0.5*6.804*31.29**2 = 3330.8 joules, or 2456.7 foot-pounds, in close agreement with your result.
The watt-hour equivalent is a puny 0.925 watt-hours. It would take a lot of speeding bowling balls to keep you warm in a 2015 winter.
Thank you...faster than I thought.
I don’t know how heavy of an object it would take to derail a train, but as a child I was warned that if I kept putting pennies on the track, it would derail the train.
(But I did. And it didn’t)
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