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NotTim
Group Title
2 canoeists, A & B, live on opposite shores of a 300.0 m wide river that flows east at 0.80 m/s. A lives on the north shore and B lives on the south shore. They both set out to visit a mutual friend X who lives on the north shore at a point 200.0m upstream from A and 200.0m downstream from B. both canoeists can propel their canoes at 2.4 m/s thru the water. How much time must canoeist A wait after canoeist B sets out so that they both arrive at X at the same time? Both canoeists make their respective trips by the most direct routes.
 one year ago
 one year ago
NotTim Group Title
2 canoeists, A & B, live on opposite shores of a 300.0 m wide river that flows east at 0.80 m/s. A lives on the north shore and B lives on the south shore. They both set out to visit a mutual friend X who lives on the north shore at a point 200.0m upstream from A and 200.0m downstream from B. both canoeists can propel their canoes at 2.4 m/s thru the water. How much time must canoeist A wait after canoeist B sets out so that they both arrive at X at the same time? Both canoeists make their respective trips by the most direct routes.
 one year ago
 one year ago

This Question is Closed

NotTim Group TitleBest ResponseYou've already chosen the best response.0
This is for a friend, so I don't have much work shown.
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
I know that B takes 125s. CALC: 1. v=2.40.80=1.6m/s 2. t=200m/1.6m/s=125s
 one year ago

Shadowys Group TitleBest ResponseYou've already chosen the best response.1
note: 2.4 is speed relative to the earth?
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
https://fbcdnsphotosaa.akamaihd.net/hphotosakprn1/533567_154212501399299_1017958671_n.jpg https://fbcdnsphotosha.akamaihd.net/hphotosaksnc7/421635_154212521399297_25972720_n.jpg https://fbcdnsphotosfa.akamaihd.net/hphotosakprn1/76140_154212481399301_1414230843_n.jpg https://fbcdnsphotosda.akamaihd.net/hphotosakash4/387012_154212484732634_845307988_n.jpg https://fbcdnsphotosga.akamaihd.net/hphotosakash4/428325_154212474732635_582085865_n.jpg https://fbcdnsphotosba.akamaihd.net/hphotosakprn1/150879_154212514732631_1274474888_n.jpg https://fbcdnsphotosda.akamaihd.net/hphotosakprn1/554471_154214558065760_366131359_n.jpg https://fbcdnsphotosha.akamaihd.net/hphotosakash3/44769_154214568065759_779969484_n.jpg https://fbcdnsphotosfa.akamaihd.net/hphotosaksnc7/486007_154214574732425_1940920149_n.jpg https://fbcdnsphotosba.akamaihd.net/hphotosakash3/537274_154214594732423_1396018523_n.jpg https://fbcdnsphotosda.akamaihd.net/hphotosakprn1/45480_154216528065563_1014789527_n.jpg
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
@Shadowys Yes, I believe so. Those links are images of an answer key I wrote down. Step 5 is indecipherable though. My friend had difficulties understanding the angle.
 one year ago

Shadowys Group TitleBest ResponseYou've already chosen the best response.1
can i use vectors to solve this?(it should be solved with vectors)
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
Wait....er. no. My friend's course probably doesn't use vectors.
 one year ago

Shadowys Group TitleBest ResponseYou've already chosen the best response.1
cos, the speed 2.4 is gonna have it's components...lol...without vectors....
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
well, go ahead and use vectors if you like. (is this vectors the basic kind, or from calculus and vectors)?
 one year ago

Shadowys Group TitleBest ResponseYou've already chosen the best response.1
dw:1359342186714:dw the basic kind. where i=unit vector in x direction, j is unit vector in y direction. the velocity of A, \(\vec v_A = 2.4\vec i +0.8i=1.6\vec i\) the displacement vector of A \(\vec S_A= 200\vec i\) so time taken for average journey = \(\frac{\vec S_A}{\vec v_A}=\frac{\sqrt{(200)^2}}{\sqrt{(1.6)^2}}=125s\) the angle of BX is \(tan^{1} 3/2=0.9828 rad \) for B, velocity of B =\(\vec v_B = 2.4(cos 0.9828 \vec i+sin 0.9828 \vec j)+0.8\vec j=2.1313\vec i + 0.832\vec j\) displacement is \(\vec S_B= 200\vec i+300\vec j\) so time taken for average journey = \(\frac{\vec S_B}{\vec v_B}=\frac{\sqrt{(200)^2+(300)^2}}{\sqrt{(2.1313)^2 +(0.832)^2}}=157.35s\) so time needed to wait=157.34s125s=32.35s
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
answer key says 6.1s.
 one year ago

Shadowys Group TitleBest ResponseYou've already chosen the best response.1
is my diagram wrong?
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
dw:1359314524260:dw yours is right. just missed a few lines
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
dw:1359314590576:dw
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
Your part A is fine, its jsut part B
 one year ago

Shadowys Group TitleBest ResponseYou've already chosen the best response.1
hmm...either it's wrong that i took 2.4 as the magnitude...what do you think?
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
The first time you used it is fine, but I'ven ever seen the 2nd time 2.4 wasused (usign ctrlF)
 one year ago

Shadowys Group TitleBest ResponseYou've already chosen the best response.1
oo, right, i forgot to multiply the j component by 2.4. so \(\vec v_B =2.1313\vec i + 1.997 \vec j\) t=123.49s....
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
Vb here was 131.15s?
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
Sorry, Tb is 131.15s
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
125s was an acceptable value too for some reason.
 one year ago

Shadowys Group TitleBest ResponseYou've already chosen the best response.1
nope.....hmm...am i overthinking this? for which reason?
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
125s was an acceptable solution for the time for B. And why? I do not know. I've looking over various different solutions and methods here (not understanding), and the values 131.15 and 125 are acceptable for some odd reason.
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
of course, 131.15s is the on on the official answer key
 one year ago

NotTim Group TitleBest ResponseYou've already chosen the best response.0
we can give it a rest now if you want.
 one year ago

Shadowys Group TitleBest ResponseYou've already chosen the best response.1
alright. hopefully someone else will give it a go.
 one year ago
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