THEORETICAL PROBLEM: The parking brake of a car weighing 3000 pounds that is 6 feet wide fails. The car is parked on a 45 degree hill and rolls backwards until it is stopped by an 8 feet long horizontal pipe which is secured at both of its ends, one foot behind the car's rear bumper. The car is not being accelerated by the engine; it is just rolling backwards into the pipe. KNOWN SPECIFICATIONS: The pipe is 8 feet long. The pipe has a 3/4" ID. The pipe can be made from either steel or pultruded fiberglass. STRUCTURAL ENGINEERING QUESTION: What would the wall thickness of the pipe need to be in order to prevent the 8 feet long pipe from flexing more than 4 inches at its center when the 3000 pound, six feet wide car rolls one foot backwards into it? LOOKING FOR THESE ANSWERS (they can be best estimates): If made from steel, the pipe would need to have a _____" thick wall. If made from pultruded fiberglass, the pipe would need to have a _____" thick wall. |