Recent content by Joel

Well, I probably don't know any more about it than you, but I understand it simply as a result from all the experiments that confirm Newton's second law. Acceleration is per definition change in motion and a bigger mass will clearly "resist a change in motion" and result in less acceleration (a...

Yes, I think you are right... And I was wrong in saying dW would be positive if work is done on the system, it is positive when the system does work on the surrounding. Sorry.

I must say don't understand this reasoning. Concidering the wording in the question, why wouldn't the 500j be the net decrease in internal energy?

Hootenanny, doesn't "on the system" mean precicely that energy is added? Wouldn't it be "on the surrounding" if the system lost energy?

You've probably thought right, but I think your notation is non-standard. It should be: U = Internal energy, W = mechanical work and Q = amount of heat added. dQ = dU + dW. All these changes are seen in relation to the system, so dU should be negative and dW positive, right?

Hi! I also think overpressure means the pressure over atmospheric pressure, in other words the net pressure that affects the ball. But I am somewhat fuzzy on exactly what should be done here, but I think the idea is that at some point during the bounce, all of the balls kinetic energy from the...

1. A fundamental property of matter that (among other things) determine how the matter reacts to a force. 2. Weight is the force on a mass due to gravity.

Me neighter, so he may just as well be faking it. Anyway, I have also been warned not to confuse ADD and ADHD with dyslexia, altough they sometimes appear in the same person. And non of these should be confused with old fascioned sloppyness. :smile:

Neat thingy! I can see my house! :approve:

Significant digits? I don't know... :confused:

My list? I don't know, a google search told me he has been cured by scientology... You probably know much more about it than I do. :smile:

I recognice this and I've had the exact same thought. I don't know if it's just because I want to think that if I'm worse at something I have to be better at something else, but I do find myself very aware of the steps in my own thoughts. It must have something to do with the countless times I...

I also have dyslexia and it sure has affected me, but not the the point where it has gotten the upper hand. In third grade a swedish teacher first guessed I had it, but I refused to believe I had any disadvantage compared to others and also refused further investigation, despite my parrents...

I think this would REALLY be an interesting election. Two educated candidates, who both has to know how low campaigns usually get and who are capable of thinking for themselves, would they have any interest in pulling up the standard?

Understanding scientific articles: "IT HAS LONG BEEN KNOWN..." = I haven't bothered to look up the original reference "...OF GREAT THEORETICAL AND PRACTICAL IMPORTANCE" = Interesting to me "WHILE IT HAS NOT BEEN POSSIBLE TO PROVIDE DEFINITE ANSWERS TO THESE QUESTIONS..." = The experiments...