Using your common sense to solve a physics problem.

What a way to make me feel stupid Lam. I thought that 'what is the next number in the sequence' thread was bad enough!I blooming hate physics But as a more pertinent point:Your problem made me think about the nature of science and its relation to common sense. I came to the conclusion that almost every scientific discipline I could think of (apart from the obviously anti-intuitive ones like quantum physics) was the application of common sense once you know the details.Of course that last bit in bold is the tricky bit, and takes a bit of time.I think this is especially true when you look at my field (biology) - in my opinion its' all about knowing the facts and applying that knowledge. The closest thing I can think of to your physics tester is those genetic phenotype diamond things I remember from my school days (he says sounding older than he is) - and they definitely can be done with pure common sense, and not much practice.

...I sat down during my lunch break yesterday and I think I've figured it out . The first time I stuck the numbers into the equations I got a rather silly answer, but common sense told me that the car wasn't trying to break the land speed record so I had another look and noticed something in the equations that I'd forgotten to do. Like I said, I think I've got it (although of course I'm not sure). In contrast to DrJones (Jerk Engineer), this Jerk Cell Biologist took all of his lunch hour to do it I had unpleasant flashbacks to my physics A levels ("Sir! I can't do it!!) Do you want to see my working? Or are you waiting for rRat to come up with the goods?On a slightly different note : Does anyone have any non-physics/maths problems that could be set ?

Okay, here’s how I think it might be done (he says preparing to look rather silly) :Use tan(d) = a/b to calculate d where a/b = 0.08 (8%)Use d in the formula:Ftotal = u_k m g cos(d) — m g sin(d)
= 4.397m — 0.781mBecause F = ma then a must equal 3.616Next :2a(x2-x1) = (V2²-V1²)Or to put it another way:2a (Distance breaked) = (Starting velocity) ²Soooo (he says hesitantly):The answer is 32.86 mphIf this is wrong but the method is OK then it is probably to do with my inability to use a calculator and a blind spot for minus numbers.If it is wrong and I’ve cocked up somewhere — give us another hint (its been driving me nuts!) Apologies to anybody else who thinks this is a bit mundane but its been doing me noodle because I know I should be able to do it, and I just have to know!!

I'm a jerk scientist who hasn't touched Physics since my A levels (10 years ago), and who could never really get to grips with the subject (angular momentum used to really do my head in).
I don't really know what that says about the point of the thread though.Although I tried to approach the problem with a kind of 'common sensical' method I would have really struggled if Lam hadn't provided the basic equations and I didn't have a basic knowledge of how to manipulate equations.

I blooming hate word games too Actually what I had in mind would be something from other sciences like chemistry, or biology.Of course it depends what Lam wanted to demonstrate in this thread. If he wanted to show that application of accumulated knowledge was a more efficient method of reasoning than 'common sense' then not only has made the point already (Riverrat refused to use the accumulated knowledge that Lam supplied, and struggled ^* ), but it could be re-emphasised by providing other examples.Take a classic Mendelian experiment crossing tall and short in-bred pea plants: I'm prepared to say that without the knowledge of genes and dominance and recessiveness then it would be nigh-on impossible to get the answer to that question by common sense alone.Naturally if the point is to set problems and provide all of the information needed to solve them then the above problem is childs play (that's biology for you), and not really worth discussing to any length.Of course, I would have had no problem with your puzzle but (gosh darn it) Jar went and did it (spelling mistakes permitting) before I got a chance * No offense meant to Riverrat on this point, I'm relatively sure he could have beaten me to the answer if he had used the equations provided

Oooh that's a good one, genetics with a twist of natural selection.I'll get back to you when I have time to sit down and think about it, as its been a while since I've done any genetic type problems and on top of that my maths is not diamond sharp (as seen earlier in the thread)

I know this is a bit of a cheeky/lazy way of going about things, but can you point out the post in which you first used the term 'jerk scientist' (I've done a bit of a search and can't find it). It might be interesting to see the initial context of the comment and whether you've softened your stance after it had the desired inflammatory effect.Cheers

Hang on a mo! I don't want to start off on the wrong foot - I didn't mean to accuse you of anything. All I was trying to do was see if I could get a summary of your position now, and compare it to the statement that started all this off. You've been throwing little bits of this into your exchanges with Percy, I just thought it would be good for you to round it all up into a single coherrant post. Correct me if I'm wrong but it seems to me that you've mellowed from the original statement.Would you accept (for example) that in order to boldly declare a theory you need to know the specific facts that are involved, and common sense alone cannot help you with this - accumulated knowledge and therefore some kind of education (of the appropriate subject) is irreplacable. That said, you must then agree that it is a bit premature to form a theory without knowing the facts?