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Author Topic: What forces are experienced when a fire truck crashes?  (Read 1372 times)

Offline gilljersey

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Hello all, I am in need of some help. I work for a fire department who had a significant fire truck crash last summer. Because of this, my department has set about making a training program for our drivers. Lucky me, I am in charge of said program.
 
So I need some help.
 
Here is the story. Last summer one of our Ladder Trucks ( fire truck with the big long ladder on the top of the truck that extends out, not a fire engine that has water) was traveling around 58 mph on a curved road then is lost traction, slide and rolled. No one was seriously hurt.
 
Here is what we know. Said ladder truck was traveling around 58 MPH and weight 62,500 lbs. I know, using the formula for kinetic energy, ( KE= 1/2 Mass X Velocity squared) that this truck produced 7,016,409.78 ft lbs or 3,508 tons of energy.
 
What I am looking for is a way so show the members of my department what that much energy looks like. As in, that kind of power in an explosion, or a wrecking ball destroying a building. I need a way to relay to my guys, the power that they are driving down the roads and highways every day.
 
Luckily when this truck crash, it only hit a telephone pole a picket fence and a few cars. The extent of the damage was very little in comparison to what could have happened.
 
I have searched the web for a way to show this and have come up with nothing. Someone suggested I try a Science blog, so I leave it up to you.  What have you got ????
 
 
And   thanks for the help.
« Last Edit: 25/09/2015 16:12:54 by chris »


 

Offline Thebox

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Hello all, I am in need of some help. I work for a fire department who had a significant fire truck crash last summer. Because of this, my department has set about making a training program for our drivers. Lucky me, I am in charge of said program.
 
So I need some help.
 
Here is the story. Last summer one of our Ladder Trucks ( fire truck with the big long ladder on the top of the truck that extends out, not a fire engine that has water) was traveling around 58 mph on a curved road then is lost traction, slide and rolled. No one was seriously hurt.
 
Here is what we know. Said ladder truck was traveling around 58 MPH and weight 62,500 lbs. I know, using the formula for kinetic energy, ( KE= 1/2 Mass X Velocity squared) that this truck produced 7,016,409.78 ft lbs or 3,508 tons of energy.
 
What I am looking for is a way so show the members of my department what that much energy looks like. As in, that kind of power in an explosion, or a wrecking ball destroying a building. I need a way to relay to my guys, the power that they are driving down the roads and highways every day.
 
Luckily when this truck crash, it only hit a telephone pole a picket fence and a few cars. The extent of the damage was very little in comparison to what could have happened.
 
I have searched the web for a way to show this and have come up with nothing. Someone suggested I try a Science blog, so I leave it up to you.  What have you got ????
 
 
And   thanks for the help.

I do not think explaining a crash to be anything similar to an explosion will help in your explanation, the force of an explosion is isotropic in nature, meaning the blast force/shock wave would travel/expand equally in all directions, providing it was not a shaped charge. where I believe the main force can be directed.
Also a wrecking ball is not a good example, walls are quite weak at a vertical altitude compared to the wrecking ball, the walls are easy to topple over.
I think you would be best explaining it in sort of Einstein terms,relatively.  if this is something you may want to consider I will gladly write you some points.

 

Offline Colin2B

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With all due respect to Mr Box, I would keep relativity out of it and keep it simple eg 3500 tons falls on you. Seems graphic enough to me.
You could equate it to a weight of TNT, but most people have difficulty imagining an explosion of say 2lb TNT unless they have worked with explosives.
 

Offline Thebox

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With all due respect to Mr Box, I would keep relativity out of it and keep it simple eg 3500 tons falls on you. Seems graphic enough to me.
You could equate it to a weight of TNT, but most people have difficulty imagining an explosion of say 2lb TNT unless they have worked with explosives.


I would say people remember flies impacting on a window screen type examples rather than relative maths. To explain that when the vehicle impacts, that every single molecule of the vehicle and every single molecule of the passengers of the vehicle, continue with forward momentum at a force equal to the speed they were travelling at, hits home harder when comparing to a fly hitting a window screen. The fire engine turns into a fly the greater speed you travel at.
Moto- the fire engine is  a fly but not a fly at the same time, if there is person you are running over, they are the fly, if it is a brick wall you are hitting, the fire engine is the fly, if you drive safe and be aware of the flies, there is no flies.


LOl no flies on me.







« Last Edit: 25/09/2015 15:52:28 by Thebox »
 

Offline chiralSPO

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I think the best way to illustrate this would be how high up the truck would need to fall from to have the same kinetic energy. If it's going 58 mph, the it would have fallen from about 112 feet (not counting air resistance). You can calculate this height for any speed by converting mph to m/s, divide that by 9.8 m/s2 to find out how long (time) it would take to fall that distance, then calculate the fall height in feet by h = *32*t2

all in meters:
a= 9.8 m/s2
t = v/a
h = 9.8t2/2

Trying to compare to explosives will give pretty unimpressive numbers (remember that the truck got all of it's kinetic energy from gasoline in its tank, and can achieve those speeds many, many times, and sustain them for hours). The kinetic energy of a 62500 lbs truck at 58 mph is less than the energy content of 0.08 gallons of gas...
 

Offline gilljersey

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Re: What forces are experienced when a fire truck crashes?
« Reply #5 on: 25/09/2015 17:30:21 »
I thank you all for your responses. What I need most is how to really this information to the common person in the simplest terms. We as not as scientifically advanced as you all are. So how would you explore all this at a 6th grader?
 

Offline alancalverd

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Re: What forces are experienced when a fire truck crashes?
« Reply #6 on: 25/09/2015 17:50:16 »
The kinetic energy was just over 19,000,000 joules. This is about the same amount of energy as you would get from burning 1 kg of wood - not a lot! - and is as much as you will extract from your food in a couple of weeks.

The problem is that you can do a lot of damage to a lot of squidgy people with 19 MJ. So how do you communicate this? The best analogy you can give anyone for being hit by a firetruck is...being hit by a firetruck.

My first driving instructor stopped the car opposite a queue of about 10 people waiting for a bus. He said "If you had a rifle, you could probably injure one of them from here - you might even kill one if you were a good shot. If you drive this car at them, you could kill them all."
« Last Edit: 25/09/2015 17:52:49 by alancalverd »
 

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Re: What forces are experienced when a fire truck crashes?
« Reply #6 on: 25/09/2015 17:50:16 »

 

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