Oz's Question of the day #210 (8/2/10)

[Fz6Sa]

Answer:,it is impossible to average 60 mph for the entire journey.

I don't get it ......
Could someone explain this answer to me?

 

[Coopdman]

I don't get it ......
Could someone explain this answer to me?

I got it wrong too, but after knowing the answer I can try to explain. Hope I'm not stepping on toes :ban:

Let's assume Mick's ride to work is exactly 30 miles. At 30mph, it took him exactly 1 hour to get there. His return trip is also exactly 30 miles. In order to average 60mph, he'd have to travel both to work and back home (60 mile round trip) in exactly one hour, and since he's already exhausted that hour on the trip in, it's an impossibility. Hope that helped.

Now the modern physics theorist will argue that although terribly improbable and requiring more energy than technologically possible, this average speed could be achieved by travelling back home at the speed of light, thus relatively stopping time for Mick for his brief trip, and allowing the 60mph average. Let's hope the pavement is dry!

 

[Fz6Sa]

I got it wrong too, but after knowing the answer I can try to explain. Hope I'm not stepping on toes :ban:

Let's assume Mick's ride to work is exactly 30 miles. At 30mph, it took him exactly 1 hour to get there. His return trip is also exactly 30 miles. In order to average 60mph, he'd have to travel both to work and back home (60 mile round trip) in exactly one hour, and since he's already exhausted that hour on the trip in, it's an impossibility. Hope that helped.

Now the modern physics theorist will argue that although terribly improbable and requiring more energy than technologically possible, this average speed could be achieved by travelling back home at the speed of light, thus relatively stopping time for Mick for his brief trip, and allowing the 60mph average. Let's hope the pavement is dry!

Thx!!!
I completely missed this point , - guess my brain is overdue for replacement

 

[MaxRyan]

Now the modern physics theorist will argue that although terribly improbable and requiring more energy than technologically possible, this average speed could be achieved by travelling back home at the speed of light, thus relatively stopping time for Mick for his brief trip, and allowing the 60mph average. Let's hope the pavement is dry!

Speed of light is actually not fast enough, it would be much closer but the true required speed would be infinite or not possible like you said.

 

[Coopdman]

Speed of light is actually not fast enough, it would be much closer but the true required speed would be infinite or not possible like you said.

In Newtonian Physics, you're correct. The finite speed of light, some 671 million miles per hour, would increase the average speed by a few millionths of a mph; But that's why I noted the modern physics theorist part.

I don't want to claim to be an expert, but General and Special Relativity show us that if it were possible to travel the speed of light, (the absolute fastest speed attainable by these theories) our perception of time will seem to stop, thus no time will pass and the trip will have happened instantaneously to the traveler, no matter the distance.

EDIT: I failed to mention time stops ONLY for the traveler. As long as Mick were doing the measurements, this theory would work. If someone stationary on Earth, took the measurements, we again have the problem of a finite speed of light and the minimal time it took him to travel home.

I know this is totally opposite from what we call logic, but I find it interesting at the least. If you're interested, check out these books/DVDs. Sorry for the long links.

[ame=http://www.amazon.com/Elegant-Universe-Superstrings-Dimensions-Ultimate/dp/0375708111]Amazon.com: The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory (9780375708114): Brian Greene: Books[/ame]

[ame=http://www.amazon.com/gp/product/B0000ZG0TA/ref=pd_lpo_k2_dp_sr_2?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=0375708111&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0Q4521FJDK0SSSCCBSWQ]Amazon.com: NOVA - The Elegant Universe: Michael Duff, Brian Greene, Michael B. Green, Walter Lewin, Joseph Lykken, Amanda Peet, John Schwarz, Maria Spiropulu, Leonard Susskind, Cumrun Vafa, Gabriele Veneziano, Steven Weinberg, Joseph McMaster, Josep[/ame]

[ame=http://www.amazon.com/gp/product/0375727205/ref=pd_lpo_k2_dp_sr_3?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=0375708111&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0Q4521FJDK0SSSCCBSWQ]Amazon.com: The Fabric of the Cosmos: Space, Time, and the Texture of Reality (9780375727207): Brian Greene: Books[/ame]

[ame=http://www.amazon.com/General-Relativity-B-Robert-Geroch/dp/0226288641/ref=pd_sim_b_3]Amazon.com: General Relativity from A to B (9780226288642): Robert Geroch: Books[/ame]

[ame=http://www.amazon.com/Physics-Impossible-Scientific-Exploration-Teleportation/dp/0307278824/ref=pd_sim_b_4]Amazon.com: Physics of the Impossible: A Scientific Exploration into the World of Phasers, Force Fields, Teleportation, and Time Travel (9780307278821): Michio Kaku: Books[/ame]

[ame=http://www.amazon.com/Hyperspace-Scientific-Odyssey-Parallel-Universes/dp/0385477058/ref=pd_sim_b_5]Amazon.com: Hyperspace: A Scientific Odyssey Through Parallel Universes, Time Warps, and the 10th Dimens ion (9780385477055): Michio Kaku: Books[/ame]

 

[OZXJR]

Great explanation Coop :thumbup: