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Math Made Fun...
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 2006-11-16 8:08 AM |
COURT JESTER  12230     ROCKFORD, IL |  Subject: Math Made Fun...Math Story Problem:
A Backhoe weighing 28 tons is on top of a flatbed trailer and heaing east on Interstate 70 near Hays, Kansas. The extended shovel arm is made of hardened refined steel and the approaching overpass is made of commercial-grade concrete, reinforced with 1 1/2 inch steel rebar spaced at 6 inch intervals in a criss-cross pattern layered at 1 foot vertical spacing.
Solve: When the shovel arm hits the overpass, how fast do you have to be going to slice the bridge in half? (Assume no effect for headwind and no braking by the clueless driver.)
Extra Credit: Solve for the time and distance required for the entire rig to come to a complete stop after hitting the overpass at the speed calculated above.
No... you can't consult the driver; he is still trying to figure out what the hell happened.
And, yes, the backhoe seems to be fine.
The question should have been ... estimate the IQ of the driver!)
(semi2.JPG) (semi1.JPG) (semi3.JPG) Attachments ---------------- semi2.JPG (78KB - 11 downloads) semi1.JPG (59KB - 12 downloads) semi3.JPG (38KB - 12 downloads) |
| 2006-11-16 8:14 AM in reply to: #600838 |
Runner | Subject: RE: Math Made Fun... I could do it with C4, but not sure about the backhoe..... |
| 2006-11-16 8:15 AM in reply to: #600838 |
Champion 8936  | Subject: RE: Math Made Fun... I still don't know the exact question, but I'm gonna go with 12. |
| 2006-11-16 8:17 AM in reply to: #600838 |
Master 2287 Calgary, Alberta | Subject: RE: Math Made Fun... That's amazing |
| 2006-11-16 8:18 AM in reply to: #600838 |
Arch-Bishop of BT 10278 Pittsburgh | Subject: RE: Math Made Fun... c... in physics it seemed the answer was always c. Question though... it doesn't seem as if the arm sliced through the edge of the bridge... the sides of the bridge are intact. Am I seeing that correctly? Despite how it feels when we land on it when we are tossed off our bikes, isn't concrete a fairly "soft" material? Peace.
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| 2006-11-16 8:20 AM in reply to: #600838 |
Pro 3673 MAC-opolis | Subject: RE: Math Made Fun... Look carefully at the pics. It appears as it the backhow went up through the overpass, not across it. Notice that there is no entry point on either side of the top of the overpass, only from underneath. The guard rails on top of the overpass are intact on both sides. How did that happen?
Edited by The Mac 2006-11-16 8:20 AM |
| 2006-11-16 8:20 AM in reply to: #600849 |
Giver 18427 | Subject: RE: Math Made Fun... I can't figure out where in teh equation to factor in "3 PBR tallboys." |
| 2006-11-16 8:23 AM in reply to: #600854 |
Runner | Subject: RE: Math Made Fun... run4yrlif - 2006-11-16 9:20 AM I can't figure out where in teh equation to factor in "3 PBR tallboys." Think that goes in the IQ question.... Oh, and while concrete is relatively "soft", the reinforced concrete is not, and additionally, they generally use pre-stressed concrete on bridges (if you've ever seen a truck carrying concrete I-beams that are rounded on top, that's what I'm talking about), and that tends to be a little more resilient. Plus, there's a section that sometimes can be a thin sheet of metal or other material called the pan, that's what the actual roadway sits on top of. Reinforced concrete is a pain in the butt to demo, because the rebar requires different amounts of charges, so you end up having to go with a larger charge overall. Plus, it sucks to cut through it. Edited by Scout7 2006-11-16 8:26 AM |
| 2006-11-16 8:33 AM in reply to: #600838 |
Expert 924 Louisville, KY | Subject: RE: Math Made Fun... I think the real math problem I'd like to see solved here is to calculate the force and velocity of the boss' foot as it enters the semi-driver's @ss. |
| 2006-11-16 8:33 AM in reply to: #600838 |
Pro 4481 Reston | Subject: RE: Math Made Fun... you're right. math is fun. |
| 2006-11-16 8:58 AM in reply to: #600852 |
Champion 7558 Albuquerque, New Mexico | Subject: RE: Math Made Fun... akustix - 2006-11-16 8:18 AM c... in physics it seemed the answer was always c. Question though... it doesn't seem as if the arm sliced through the edge of the bridge... the sides of the bridge are intact. Am I seeing that correctly? Despite how it feels when we land on it when we are tossed off our bikes, isn't concrete a fairly "soft" material? Peace.
Cool, Tupuppy! Akustix, Great observations. If I were to "reconstruct" the incident, I'd guess that the boom-stick joint impacted the overpass below the deck. I'd guess the boom was pointed forward (initially) and the resulting forces pushed the joint up through the overpass as the boom "hyper-extended" into the final position. No, the excavator is not "fine". The boom is hyperextended back into the engine compartment and the bucket cylinder is separated. As for concrete, Tupuppy is the real expert. Concrete has pretty good compressive strength (resists compression) but horrible tensile strength (is easily pulled apart), hence the rebar reinforcements. I would not ever consider it "soft" unless it is uncured. We had a similar episode downstate, where the driver missed 6" in his calculation of bulldozer (cab) height plus trailer height. Edited by McFuzz 2006-11-16 9:03 AM |
| 2006-11-16 9:00 AM in reply to: #600838 |
| Crystal Lake, IL | Subject: RE: Math Made Fun... I think the arm in the last picture has been forced upwards as they tried to dislodge the machine underneath. The initial impact might have forced the bed of the trailer down on its airbags (suspension) and then the recoil effect jammed the arm back up against the underside of the bridge. |
| 2006-11-16 9:09 AM in reply to: #600838 |
Champion 5529 Nashville, TN | Subject: RE: Math Made Fun... That is awesome. My guess if 45 mph with some freak outside force causing the problem. Could you imagine being a motorist on the bridge. It would be a surreal moment, something from the movies. |
| 2006-11-16 9:13 AM in reply to: #600838 |
COURT JESTER 12230 ROCKFORD, IL | Subject: RE: Math Made Fun... Drivers call to the boss immediately afterward: "Boss, I QUIT!!" |
| 2006-11-16 11:36 AM in reply to: #600838 |
Champion 6285 Beautiful Sonoma County | Subject: RE: Math Made Fun... My answer: $134,000 From snopes.com: http://www.snopes.com/photos/accident/hoecrash.asp The driver of the rig was uninjured, although he was later cited for not having clearance to drive on the interstate. The Kansas Department of Transportation said the construction company for which the driver worked would be liable for the cost of repairs to the overpass, which were estimated at $134,000 as of late March 2006. |
| 2006-11-21 4:35 PM in reply to: #600838 |
Regular 82 | Subject: RE: Math Made Fun... what do you mean math made fun?? Math already is fun!!!!That`s why I want to be an enginer, because I like math and science. |
| 2006-11-21 4:49 PM in reply to: #605687 |
COURT JESTER 12230 ROCKFORD, IL | Subject: RE: Math Made Fun... TriGirl10 - 2006-11-21 3:35 PM what do you mean math made fun?? Math already is fun!!!!That`s why I want to be an enginer, because I like math and science. I AM an engineer (civil). Math was never FUN....just wasn't difficult (not counting Differential Equations, Calculus 2 & 3) |
 2006-11-22 11:47 AM in reply to: #600838 |
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