Using your common sense to solve a physics problem.

We have PM here? Strange that I've been missing that all along. Where can I go to see mine?

---

The Laminator
B ULLS HITFor goodness's sake, please vote Democrat this November!

No, you could derive the forumla from the problem I presented, knowing as we do that we live on Earth.It would just take a long time. The problem is a lot harder to solve from first principles; so hard, in fact, that the odds that the untrained won't make a fatal error are very, very slim.

Hahaha. True. I haven't done kinematics for 2 years and am too lazy to look into it now.

---

The Laminator
B ULLS HITFor goodness's sake, please vote Democrat this November!

Oh, I'm too used to built in PM features; E-mailing would be equivalent.

I see your message has already drawn some replies, so maybe this is redundant, but Lam posted the problem to illustrate that common sense can often lead you astray. There are many types of problems for which the answers are unintuitive.I think it's great that you want to solve the problems posed by Crash and Lam, but solving the problems wasn't why they posted them. They posted them to illustrate the great error in your characterization of an entire class of people as "jerk scientists" who with all their education and training can be matched with simple common sense.It would be nice if we could better equip scientists for their profession by providing them less education so that their common sense wasn't suppressed by all those darn niggling facts, but gee, things just don't turn out to work that way. If they did then you would have already solved these problems, but you haven't, have you? And that's because common sense is a poor substitute for knowledge.You recently wrote that you didn't have the opportunity to go to college, but that you feel you make up for it by learning on your own. I think you'll find that the more you learn, the more uncommon your sense will be, but you'll have improved analytical skills and a much broader base of knowledge upon which to draw, and you'll be all the better for it.--Percy

But isn't $45K Canadian around the $30K American that RiverRat mentioned?I don't think $30K American is a salary being offered to engineering graduates anywhere in the states. I don't know about recently (I got out of management a while back), but 10 years ago we were offering starting salaries of around $50K to recent masters graduates in software engineering. With inflation I imagine it would be around $65K now. A bachelors degree might draw $50K today. A 2-year tech college graduate might get offered around $30K to do tech-support/computer-maintenance type work, but I can't imagine anything less than that, though perhaps in regions of the country far from hi-tech centers...--Percy

Well its closer to $35K in exchange. I shouldn't have added the "Canadian Dollars" line as it is irrelevant. The canadian dollar has as much buying power in Canada as the US dollar does in the states. So an engineer making C$30K here is just as crazy as an engineer making $30K there.This message has been edited by DrJones*, 09-23-2004 07:01 PM

---

*not an actual doctor

You seem to not want to cover a basic physics problem with your common sense. Fine, given your remarks insulting engineers, lets give you an engineering problem.You're building a double-layer catwalk in a hotel. The catwalk's mass is supported by steel hangar rods that run from the ceiling, through the upper catwalk, and down to the lower catwalk; a nut on the rod 6.1 meters up from the base holds up the first catwalk, and a nut at the end of the rod holds up the second catwalk.You find that you can't get a hangar rod which will allow you to have a nut 6.1 meters up from the base. Using your common sense, what would be the ramifications of using two hangar rods - one from the ceiling to the upper catwalk (with a nut at the bottom of the catwalk), and then one from the upper catwalk to the lower catwalk (with a nut above the upper catwalk to support the rod, and one below the lower catwalk to support the catwalk)? Would it have the same carrying capacity, reduced carrying capacity, or increased carrying capacity, and if different, how much?

---

"Illuminant light,
illuminate me."

Nothing like examples from the real world, only about 300 miles from you. July 17, 1981.--Percy

Ok so tell me, there is an aluminum I beam. It is attached at one end by a horizontal pin. The beam 12 feet long. The beam gets lifted from a point that is 8 feet from the pin. The end of the beam must carry a load of 3000lbs to a hieght of 6 feet from level.What thickness should the I-beam be, and what should the dimensions of the I-beam be, and what kind of aluminum should you use?Take as much time as you want.

I would like the mass of the car, even though you may not need it, I might so that it will lead me to the answer. There could be more than one way of figuring it out. I am not trained, so I will most likely be taking the long way.A variable could be the condition of the road on that day. Dry and wet are not the only conditions. Dew points and oil build up before a rain can affect traction conditions.The condition of the shocks and springs in the car can greatly affect how long it takes for a car to stop, as well as air pressure in the tires. Temperature of the tires at the time of lock-up can change a tires Uk. These are common sense things.

Me too. But the engineer is not the final word. This has been proven over and over again. Even when the data is correct, it is still subject to human error. If the engineer walks around with a head the size of yours, thats when the problems start.It's like I said, a combined effort is the best one. Many times the engineers can listen to the mechanics and learn something, or see something that couldn't be seen on paper.

Can I ask you a question? Why if I write this: You choose to over look that and only quote this: Isn't obvious where my attitude is at? Then you haven't meet enough engineers, or you are still honing your skills, and when you reach that eliteness or (l33tness) you will notice more jerk engineers. That is not to say that they aren't just as many jerk mechanics. refer to my 80% rule.80% of all people in all trades and professions aren't really that good at what they do, and most of that 80% borders on sucking. Try to find a good doctor, try to find a good car mechanic, go-ahead, I dare you. Probably because it has nothing to do with Uk.But I want it so I can see the whole problem. remember I am figuring this out the hard way most likely, because I have no training in it. But I will figure it out. I already have the basics as you can see. I just need to apply it in a formula. Knowing the mass of the car will help me understand Uk, better and gravity+sin(d)BTW I never took trig, I figured it out on my own, without a book, because I was a Sheet metal layout mechanic for 13 years. So with all the constant shaping of things from 2d to 3d, I needed to know about triangulation, which lead me to figure out sin and tan, except I never called it that. I can triangulate anything, I can cover you in metal, all I need is a 3 view picture of you, then your tin.

I think I have the formula, and I was doing that with M. I just want to see some things. I am a complex person, and I need to see the whole picture, which will lead me to the answer more quickly. Thanks for the help, but I will get it. I already understand whats going on, its just putting it in a formula.

Ok, if you must. The mass of the car is 1 gram.

---

The Laminator
B ULLS HITFor goodness's sake, please vote Democrat this November!