• Support PF! Buy your school textbooks, materials and every day products Here!

Vectors problem help please

  • Thread starter link107
  • Start date
  • #1
10
0

Homework Statement


A man walks 5 m at 37degrees north of east and then 10 m at 60degrees
west of north. What is the magnitude and direction of his net
displacement

The answer is around 9.3m at around 120 degrees angle on the +x axis

Homework Equations


none


The Attempt at a Solution


http://img825.imageshack.us/img825/2570/vectors2.png [Broken]

I have no idea what to do after I plot out the vector and connect tip to head. Can someone explain to me how to solve for vectors effectively?

Thank you
 
Last edited by a moderator:

Answers and Replies

  • #2
phinds
Science Advisor
Insights Author
Gold Member
2019 Award
16,091
6,088
One way to go after it is to draw right triangles and use them to find the end points in XY coordinates of what you have in the drawing. See if you can figure out what I'm talking about.
 
  • #3
54
0
Another way is to resolve the vectors along x and y axis

5m 37degrees north of east can be written as cos(37)*5 along x axis and sin(37)*5 along y axis

similarly do it for other vector..

now add components along x and y axis seperately and get new measurements along x and y axis

now use x2+y2 = (magnitude of resultant)2
for magnitude

and arctan(y/x) for direction of resultant vector.(x and y are values of new measurements along x and y axis) (angle obtained is the angle from +ve x axis)
 
  • #4
6,054
390
now use x2+y2 = (magnitude of resultant)2
for magnitude
You really surprise me. You can't figure out how to obtain the distance between two points given their coordinates, yet you advise others precisely on how this is done.
 
  • #5
54
0
Did i make a mistake??
 
  • #6
6,054
390
Did i make a mistake??
No you did not. That's why I am surprised. Why can't you apply this same knowledge to your problem about the moment of inertia?
 
  • #7
54
0
Basically i got it

But pls help me with the double integration

i mean how is it done??
 

Related Threads on Vectors problem help please

  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
6
Views
6K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
1
Views
733
  • Last Post
Replies
1
Views
2K
Replies
13
Views
3K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
2
Views
1K
Top