## Search found 20 matches

Thu Jul 21, 2011 9:11 pm
Forum: Physics Questions
Topic: Deriving the equation for length contraction and e=mc^2
Replies: 4
Views: 7339

### Re: Deriving the equation for length contraction and e=mc^2

could you please go into more detail regarding the light-year method of deriving length contraction? i don't seem to be able to bash the maths out, from my interpretation of your method. and apparently my train thought experiment apppears to be invalid and doesn't work; i need to use a mirror to ref...
Thu Jul 14, 2011 5:32 pm
Forum: Physics Questions
Topic: Deriving the equation for length contraction and e=mc^2
Replies: 4
Views: 7339

### Re: Deriving the equation for length contraction and e=mc^2

in the 1st method, is it simply because of the notation? is x' is the position of the moving object from the moving frame and so that correlates to x_2- x_1 i.e. L_0?
Thu Jul 14, 2011 5:16 pm
Forum: Physics Questions
Topic: Deriving the equation for length contraction and e=mc^2
Replies: 4
Views: 7339

### Deriving the equation for length contraction and e=mc^2

what am i doing wrong in deriving the equ of length contraction & why? 1st Method: Using Lorentz transformation #1, x' = (x-ut)/rt(1-(u^2)/(c^2)) I thought L_v = x'_2 - x'_1 simplifies to (x_2-x_1)/rt(1-(u^2)/(c^2)) = L_0/ rt(1-(u^2)/(v^2)) however for correct equ, L_0 = x'_2 - x'_1and L_v = x_2...
Sun Jul 10, 2011 11:03 am
Forum: Physics Questions
Topic: On Orbital Decay
Replies: 2
Views: 7296

### On Orbital Decay

LEOs experience orbital decay when exposed to the fringes of the earth's atmosphere, causing friction. Friction implies a decrease in Kinetic energy(?) which is converted to heat. LEOs however drop to a lower orbit meaning they increase in KE while decreasing in GPE and then due to greater KE experi...
Sun Jul 10, 2011 10:45 am
Forum: High School Physics
Topic: Feedback from the article 22 April, Sydney Morning Herald,
Replies: 10
Views: 27099

### Re: Feedback from the article 22 April, Sydney Morning Herald,

[contd.] I also agree on the comment about the lack of proper physics teachers. In my high school out of all the teaching staff there was only one physics teacher I actually had a good deal of expertise on the subject. Others would buckle under the slightest probing for the explanation of physical c...
Sun Jul 10, 2011 10:44 am
Forum: High School Physics
Topic: Feedback from the article 22 April, Sydney Morning Herald,
Replies: 10
Views: 27099

### Re: Feedback from the article 22 April, Sydney Morning Herald,

so many years, the politicians/BOS haven't listened. disappointment!! The greatest worry of all to me is that many kids who would have loved physics in its proper form will instead develop a hate of it - due to the emphasis on essay-writing/memory work (worth many marks depending on your exact wordi...
Sun Jul 10, 2011 1:08 am
Forum: Physics Questions
Topic: VERY interesting physics problem!!! :O
Replies: 1
Views: 5567

### VERY interesting physics problem!!! :O

There are two identical chambers, A and B containing identical metal balls initally at the same temperature. Each chamber is a perfect vacuum and has thermally conducting walls at a lower temperature than the balls. In A the ball is resting on the floor, which is made of material which is a perfect ...
Thu Jul 07, 2011 1:08 pm
Forum: Physics Questions
Topic: Rolling container filled with fluid
Replies: 1
Views: 5391

### Rolling container filled with fluid

what is REALLY interesting is that there was a guy who did an experiment similar to what Joe did in the lectures - whether a solid can rolls faster than one with liquid inside. to test this he sealed ice in a bottle with a rod through it, and also liquid water in a bottle with a rod through it. he r...
Sat Jul 02, 2011 2:07 am
Forum: Physics Questions
Topic: Warning Shot.
Replies: 2
Views: 6238

### Re: Warning Shot.

also, i wasnt sure whether or not police are in fact allowed to fire warning shots... so i did a google search, didn't come up with much reliable information but found that "Officers would risk internal disciplinary action by firing warning shots to control an armed offender. Police tactical or...
Sat Jul 02, 2011 1:30 am
Forum: Physics Questions
Topic: Warning Shot.
Replies: 2
Views: 6238

### Re: Warning Shot.

Could you please list your sources/references... was the experiment you described from the mythbusters episode "bullets fired straight up?"
Sat Jul 02, 2011 12:35 am
Forum: Physics Questions
Topic: Quite Interesting.
Replies: 6
Views: 12424

### Re: Quite Interesting.

Unless that someone is a physicist... :lol: but even so, feathers would still be measured in SI units unless you happen to live in north America. Regardless, once you reduce that question down to a matter of linguistics of units, it loses any scientific meaning... it becomes a question of perhaps hi...
Sat Jul 02, 2011 12:15 am
Forum: Physics Questions
Topic: Quite Interesting.
Replies: 6
Views: 12424

### Re: Quite Interesting.

That is definitely not true if you are using SI units, the METRIC tonne which is NOT based on imperial units (pounds) which is what your two systems are referring to.
Thu Jun 30, 2011 2:13 am
Forum: Physics Questions
Topic: Does Higher Temperature Water Freeze Faster?
Replies: 12
Views: 12013

### Re: Does Higher Temperature Water Freeze Faster?

hahaha you're way too rigorous and analytical for me!! i just frankly have no idea :P can't wait see what joe is going to say. sorta reminds me of the phenomena of lightning - such a common occurence but yet one clearcut complete explanation. and also the "how do aeroplanes fly" with berno...
Wed Jun 29, 2011 10:48 pm
Forum: Physics Questions
Topic: Does Higher Temperature Water Freeze Faster?
Replies: 12
Views: 12013