Engineering Problem

[Mark]

Subject: Engineering Problem

A backhoe weighing 8 tons is on top of a flatbed trailer and heading east on Interstate 70 near Hays, Kansas USA at 65mph. 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.

Problem: 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 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.

See below for the correct answers .......















The correct answer - Who cares, the trucking company just bought themselves a bridge.

 

[Larry L.]

hmmm 65mph 8 tons 1 1/2 steel rebar near Hays= mash nose on windsheild.

I think if I was the driver I would have got out running and run and run and run somemore before I said yeah I did dat.

 

[McMoo]

Would have though the backhoe would have came off long before it did that much damage! Make for nice pictures , news at 11

 

[James S]

I used to work for a construction company and a driver had a 15-ton trackhoe on top of a tilt-bed trailer. He didn't have the boom lowered enough and hit the overpass. When he hit, all it did to the bridge was bend the steel I-beam underneath. It broke all four chains off the trackhoe and it skidded down the road about 70 feet. When all was said and done with, the driver cranked the hoe right up, loaded it up and hauled a$$.