A river is flowing from west to east at aspeed of 5 metrs per minute. A man on th south bank of the river, wants to swim across the river in th eshortest time. He should swim in whish direction?
2007-01-21 04:04:40 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Physics
If it doesn't matter where he ends up on the other side, he should swim directly north.
2007-01-21 04:10:50 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Swim north... The velocity of the river would just change his direction eastwards a bit but wont affect his speed.
In case, he prefers to swim a bit towards north west to shorten the distance travelled, this would actually impact his speed and increase the time frame.
Swimming towards north east would just increase the distance and hence the time frame.
2007-01-21 07:35:35 · answer #2 · answered by plato's ghost 5 · 0⤊ 0⤋
my dear friend ,
man should swim across the river ..perpendicular to the velocity of river .. the river velocity causes drift and man's velocity across the river helps him crossing the river in shortest time .the velocity component of the man's velocity that helps him crossing the river is max when it's in perpendicular to velocity of river...
moroever if u dont want drift ,make such angle of the man's velocity with the river velocity so that man's velocity 's one component cancels the rivers velocity..
2007-01-21 18:27:44 · answer #3 · answered by rahul 1 · 0⤊ 0⤋
you're on the main suitable music. the gap may be the comparable, so if v(b) is the fee of the boat relative to the river and v(r) is the fee of the river, then {v(b) + v(r)} t(a million) = {v(b) - v(r)} t(2) however the left bracket is only 10 km/h and the main suitable bracket is 6 km/h. From those expressions you will get the fee of the river (and additionally the boat).
2016-12-16 09:52:07 · answer #4 · answered by ? 4 · 0⤊ 0⤋
Man's velocity is needed the shortest vector by any method will give the direction I believe mathematically 45 degrees. if velocities are same.
2007-01-21 06:40:43 · answer #5 · answered by minootoo 7 · 0⤊ 0⤋
he should swim towards west with the angle of sin inverse 5/2v .
i am explaining you how :-
1.To travel in shortest time he should travel at shortest distance.
2. Let the shortest distance is 'd' which is perpendicular
3. he now swim towards west with angle theta.
4. there is two equation vcosQ * t =d
5. second equation is (5-vsinQ) *t=dtanQ ( i am using Q for theta)
solve them and get your answer
2007-01-21 04:33:12 · answer #6 · answered by Anonymous · 0⤊ 0⤋
perpendicular to the velocity of the river
2007-01-21 04:13:30 · answer #7 · answered by 7 · 0⤊ 0⤋