Search found 474 matches

by joe
Wed Jun 03, 2015 10:24 am
Forum: Physics Questions
Topic: What is beyond Newton's and Einstein's discoveries?
Replies: 34
Views: 25983

Re: What is beyond Newton's and Einsteins's discoveries?

The strength of maths comes because it is not related to technologies, physics or the world. (Or length.) Of course, the areas of maths which have been the most used (and therefore probably the most developed) are those which have useful applications in the world and perhaps especially in physics. I...
by joe
Tue Jun 02, 2015 8:50 am
Forum: Physics Questions
Topic: What is beyond Newton's and Einstein's discoveries?
Replies: 34
Views: 25983

Re: What is beyond Newton's and Einsteins's discoveries?

It's interesting how biology and culture flavour our observations. We have a nervous system that prioritises stimuli that change (perhaps because a crocodile is more dangerous than a log). So we tend to think of the static as the 'natural' state (cf Aristotle). Imagine beings that were blind and who...
by joe
Mon Apr 27, 2015 4:15 pm
Forum: Physics Questions
Topic: Resistance?
Replies: 1
Views: 5374

Re: Resistance?

On average, the electrons don't slow down. Rather, resistance has the effect that a non-zero electric field is necessary to maintain an average speed. See the section on this in Physclips: http://www.animations.physics.unsw.edu.au/jw/drift.html The work done by that field on the electrons is turned ...
by joe
Sat Apr 25, 2015 5:51 pm
Forum: Physics Questions
Topic: Mathematical obscuration?
Replies: 30
Views: 27755

Re: Mathematical obscuration?

The graph on the article you cite: http://en.wikipedia.org/w/index.php?tit ... no#Physics is clear enough. The RHS is not the sum of the LHS, rather it is the f(0) of a smooth function that approximates f(n) = 1+2+3+…+n So it's not (obviously) equality in the usual sense. Thanks for bringing it to m...
by joe
Sat Apr 25, 2015 2:58 pm
Forum: Physics Questions
Topic: Mathematical obscuration?
Replies: 30
Views: 27755

Re: Mathematical obscuration?

That is indeed bizarre. I'll bite, what strange use of "=" are you using?
Joe
by joe
Thu Apr 16, 2015 12:20 pm
Forum: Physics Questions
Topic: Inertia in Linear and Rotational motion?
Replies: 21
Views: 35189

Re: Inertia in Linear and Rotational motion?

now I must learn waves, sound
Then have a look at:
http://www.animations.physics.unsw.edu.au/waves-sound/
and perhaps even our lab's outreach site:
http://newt.phys.unsw.edu.au/music/

Joe
by joe
Thu Apr 16, 2015 8:00 am
Forum: Physics Questions
Topic: Inertia in Linear and Rotational motion?
Replies: 21
Views: 35189

Re: Inertia in Linear and Rotational motion?

Moment of Inertia, as I was explained, is treated by some to be mass itself in Linear motion. This is confused. See the real definition, with explanation, at http://www.animations.physics.unsw.edu.au/mechanics/chapter10_rotation.html As I've said before, there is an interesting question about inert...
by joe
Wed Apr 15, 2015 9:49 am
Forum: Physics Questions
Topic: Inertia in Linear and Rotational motion?
Replies: 21
Views: 35189

Re: Inertia in Linear and Rotational motion?

1. Inertia is no any means taken into account in Linear motion formulas (Kinetic energy, momentum etc.). Why does it happen so? Applying Newton's second law to rotating objects results in torque = I*angular acceleration Calculating the kinetic energy due to rotation gives K = 1/2 I omega^2 If there...
by joe
Wed Apr 15, 2015 9:48 am
Forum: Physics Questions
Topic: Inertia in Linear and Rotational motion?
Replies: 21
Views: 35189

Re: Inertia in Linear and Rotational motion?

2. What if define any mass by Inertia, not how it does now Inertia by mass? You'll notice that I try to avoid using 'inertia' except in 'moment of inertia'. The meaning of inertia is not unanimous. Wikipedia says "Inertia is the resistance of any physical object to any change in its state of mo...
by joe
Sat Mar 21, 2015 1:00 pm
Forum: Physics Questions
Topic: Mathematical obscuration?
Replies: 30
Views: 27755

Re: Mathematical obscuration?

multiplication of the same two numbers should result in a bigger number than that of adding these numbers! That is true for the natural numbers greater than one, because it's a special case of the algebraic explanation quoted above. But what about for rational numbers, i.e. numbers of the form n/m ...
by joe
Fri Mar 20, 2015 2:05 pm
Forum: Physics Questions
Topic: Force Vector Component?
Replies: 35
Views: 31975

Re: Force Vector Component?

Have a look at Physclips' introduction to vectors: http://www.animations.physics.unsw.edu.au/jw/vectors.htm and especially the sections on unit vectors and scalar products. The component of a in the direction of b is just a times the cos of the angle between a and b . You know from the definition th...
by joe
Fri Mar 20, 2015 1:54 pm
Forum: Physics Questions
Topic: Mathematical obscuration?
Replies: 30
Views: 27755

Re: Mathematical obscuration?

Could someone explain why adding two positive numbers results in a bigger number them multiplying these numbers? Why it is so? First, it isn't always so. 3 + 3 < 3*3. Let a = (1+x), b = (1+y) ab = 1 + x + y + xy = (a + b) + (xy – 1). So your statement is true only if xy < 1. If we think of the numb...
by joe
Fri Mar 20, 2015 1:43 pm
Forum: Physics Questions
Topic: Unit vector and direction cosines?
Replies: 2
Views: 6987

Re: Unit vector and direction cosines?

Gday Boris,

you have a diagram a bit like the one in
http://www.animations.physics.unsw.edu. ... ors.htm#3d
You might want to consider the vector that I've called h – the projection onto the x,y plane.
Take the components here, and then consider the z components

Best
Joe
by joe
Thu Jan 01, 2015 7:27 am
Forum: Physics Questions
Topic: What is beyond Newton's and Einstein's discoveries?
Replies: 34
Views: 25983

Re: What is beyond Newton's and Einsteins's discoveries?

Thanks Boris,

and good luck to you, especially with your thirst for understanding!

Joe
by joe
Wed Dec 31, 2014 10:02 am
Forum: Physics Questions
Topic: Physics Competition
Replies: 3
Views: 7111

Re: Physics Competition

Sorry, you've missed the deadline for 2014 – try again in 2015.
Joe