Question

How do I solve these types of problems?
'A ferry heads west across a river. It travels 20 miles per hour in still water. The river flows south at 15 miles per hour. In which direction will the ferry actually travel. How fast will it travel?'
I need someone to explain this, so that I can do the other problems like it.

Answer 1

its a vector related problem

Answer 2

add the vector to get the red travel distance vector

Answer 3

<20,0> is the westward vector ; and <0,-15> is the southward vector

Answer 4

the new vector is simply:

<20,0>
<0,-15>
--------
<20,-15>

Answer 5

the direction traveled is the tan^-1 (y/x) + pi

Answer 6

-15/20 = -3/4

tan^-1(-3/4) =abt 233.13 degrees if i did it right

Answer 7

had to add 270 to it to get itin the proper qudrant

Answer 8

and the distance traveled is just the pythag of the y and x components

Answer 9

any of this make sense?

Answer 10

No...I wish though.

Answer 11

hmm.... a vector is just an arrow that points in any direction and indicates the distance traveled; they can be called directed line segments

Answer 12

when we add them, they form a new arrow that measures a new direction and length

Answer 13

you essentially have the ferry being thrown off course by the river; by 15 meters every sec right?

Answer 14

well; 15 miles for every hour travled

Answer 15

if we pythag the new direction; we get 20 west; and 15 south; those are the legs of a triangle and the distance actually covered in one hour is the hypotenuse of that triangle

Answer 16

sqrt(20^2 + 15^2) = distance traveled in one hour

Answer 17

in this case; its moved 25 miles in one hour...... or 25 mph

Answer 18

the direction it moved is to the south and west...measured from some starting point; usually idicated as due est

Answer 19

due east is the inital starting point of angle measures...

Answer 20

any of this ringing bells yet :)

Answer 21

I understand better now, thank you for helping me so much :)