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It's just totally wrong! You multiply something bigger that ##v## by ##10## and get ##3v##? Come on!kimiko333 said:but why is this so? I'm supposed to get 12. And I get 12 with the second equation
It's just totally wrong! You multiply something bigger that ##v## by ##10## and get ##3v##? Come on!kimiko333 said:but why is this so? I'm supposed to get 12. And I get 12 with the second equation
Oh Jesus. I forgot to multiply v by 10. Aaaahhhh. Told you... I'm tired :DPeroK said:It's just totally wrong! You multiply something bigger that ##v## by ##10## and get ##3v##? Come on!
That's the units you used when you set ##t_1 = 10##. That's time in units of "time for a step". In those units ##v = 1## (meaning ##1## step per time for a step).kimiko333 said:Now it's 12, okay. But if I substitute in, I get 12v, not just simply 12. How do I know, that the answer is in steps?
Ooooh, okay. Totally makes sense! Great! Thank you! :D Now I just have to figure out, why is it that I can easily solve problems in electrodynamics, thermodynamics, etc, but don't know how to deal with these... :D (I'm a teacher-student, studying to be an English and Physics teacher)PeroK said:That's the units you used when you set ##t_1 = 10##. That's time in units of "time for a step". In those units ##v = 1## (meaning ##1## step per time for a step).
When you come to study Special Relativity, you'll find this is an amusing analogy to setting the speed of light ##c = 1##!
Alternatively, you could have left time in unspecified units, whereby:
##L = \frac{6}{5}vt_1##
And ##vt_1 = 10## steps.
You started off with the assumption that the quantities could be determined. But, actually, the only things that could be determined were the relationships between quantities. You end up with 12 steps, but that's true whatever the speed of the walker and beam. All we've found is that one is 5 times the other - but, they could be anything.kimiko333 said:Ooooh, okay. Totally makes sense! Great! Thank you! :D Now I just have to figure out, why is it that I can easily solve problems in electrodynamics, thermodynamics, etc, but don't know how to deal with these... :D (I'm a teacher-student, studying to be an English and Physics teacher)
Great answers! Thank you for the explanations! :) I'm grateful!PeroK said:You started off with the assumption that the quantities could be determined. But, actually, the only things that could be determined were the relationships between quantities. You end up with 12 steps, but that's true whatever the speed of the walker and beam. All we've found is that one is 5 times the other - but, they could be anything.
This is the sort of problem that undermines the "plug-and-chug" approach - too many unknowns, you said. Well, everything is still an unknown, because we don't know how long a step is or how fast anything is moving.
Finally, there is a difference between a problem being elementary and being difficult. This is an elementary problem that really made you think. You might have an advanced EM problem that involves advanced concepts but only requires you to plug the given numbers into the correct formula - so it's advanced but easy.