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Adding magnitude of vector

  • Thread starter vorse
  • Start date
  • #1
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0

Homework Statement



A vector of magnitude 20 is added to a vector of magnitude 25. The magnitude of this sum might be:
A. Zero
B. 3
C. 12
D. 47
E. 50


Homework Equations



Probable the Pythagoreans and use of sin, cos, etc.

The Attempt at a Solution



Not sure how to add the magnitude of vector w/out knowing the angle or the different components.



Thanks for looking at the problem.
 

Answers and Replies

  • #2
LowlyPion
Homework Helper
3,090
4

Homework Statement



A vector of magnitude 20 is added to a vector of magnitude 25. The magnitude of this sum might be:
A. Zero
B. 3
C. 12
D. 47
E. 50

Homework Equations



Probable the Pythagoreans and use of sin, cos, etc.

The Attempt at a Solution



Not sure how to add the magnitude of vector w/out knowing the angle or the different components.

Thanks for looking at the problem.
Welcome to PF.

Maybe eliminate the answers that aren't possible?
 
  • #3
13
0
I know what the answer it. I just don't know how the answer key got there. There are some rules that constrain the addition/subtraction of magnitude of vectors, but I don't know what they are. I am searching the net but to no avail.


P.S
Thanks for the welcome.
 
  • #4
rock.freak667
Homework Helper
6,230
31
I know what the answer it. I just don't know how the answer key got there. There are some rules that constrain the addition/subtraction of magnitude of vectors, but I don't know what they are. I am searching the net but to no avail.


P.S
Thanks for the welcome.

If you have those two force acting on a body, when would the resultant force be maximum and when would they be minimum?
 
  • #5
LowlyPion
Homework Helper
3,090
4
I know what the answer it. I just don't know how the answer key got there. There are some rules that constrain the addition/subtraction of magnitude of vectors, but I don't know what they are. I am searching the net but to no avail.

P.S
Thanks for the welcome.
You know that depending on direction a vector can be added head to tail right? So the biggest value the result can be is ... |20| + |25|

Likewise the smallest value the result can be is when they are in opposite directions. |25| - |20|

Looks like there is only one answer that satisfies these conditions.
 
  • #6
13
0
You know that depending on direction a vector can be added head to tail right? So the biggest value the result can be is ... |20| + |25|

Likewise the smallest value the result can be is when they are in opposite directions. |25| - |20|

Looks like there is only one answer that satisfies these conditions.

Yea, this was the rule I was looking for. Thanks a lot Pion.
 

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