Can anyone solve this for me ? (I got the problem in an old Physics Olympiad Book........)
A swimmer can swim in still water at a speed of 8 km/h. The river flows at the rate of 5 km/h. If the swimmer keeps himself at 130 degrees with the river flow and tries to cross the river 1 km wide, find the coordinates of the point where he'll end up .
2006-09-18 01:30:07 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Do a little vector math. Draw a picture and solve the triangles.
Using Side-Angle-Side
a^2 = b^2 + c^2 - 2 b c cos(e)
a^2 = 5^2 + 8^2 - 5*8*cos(130)
a^2 = 25 + 64 - 40*Cos(130)
a = 10.71
Cos (g) = (10.71^2 + 5^2 - 8^2 ) / (2*10.71*5)
g = 45 degrees
Actual swim direction is 45 degrees
So the position down river is 1 km across and 1 km down
2006-09-18 01:52:42 · answer #1 · answered by Grant d 4 · 1⤊ 0⤋
OOOOhhhh,but tat`s too simple! you simply take 130 deeg... ...you then try to find the ???,,,et puis zut! tat`s too simple 4 me to giv you the answer... Naaaaah.am just jokin` dear,i did that in addmaths,first draw a diagram,find the new track of the swimmer if he is 130 deeg wid river flow,if am not wrong apply pythagoras,sine rule or cos rule,u`ll surely get the ans.just try.
2006-09-18 01:52:18 · answer #2 · answered by sweetfloss8 2 · 1⤊ 0⤋
Is his 130 degrees heading upstream or downstream?
Not that I can remember enough math to get it right the first time anyway.....:-)
But at 130 degrees this swimmer will be v-e-r-y tired before reaching the other bank.
2006-09-18 01:37:57 · answer #3 · answered by whoknew 4 · 0⤊ 1⤋
It can be (-.08, -1) or (2,1)
2006-09-18 02:28:51 · answer #4 · answered by lakshmi 1 · 0⤊ 1⤋