## mathaterme2 2 years ago Make a sketch to show the given vectors. A force of 342 lbs. acting on an object while a force of 454 pounds acts on the same object an angle of 94 degrees with the first force.

1. punnus

how is the 342 lbs force acting on the object.

2. agent0smith

|dw:1361091618581:dw|

3. punnus

@agent0smith The phasor diagram will be correct only if the 342 lbs is acting horizontally on the object.

4. agent0smith

@punnus it shouldn't matter, only thing that should be important is angle between vectors.

5. agent0smith

|dw:1361091942621:dw| We don't know the resultant direction of course, but still, it doesn't appear to be important.

6. punnus

It is a phasor diagram it is the representation on the forces acting on it .. All i am saying that same information has to given regarding the 342 lbs force. If we go about only the relation between 342 and the 454 lbs force then is not a fully correct diagram as it does no such justification to the 342 lbs force @agent0smith

7. agent0smith

Well yeah, but all it asks to show the angle between them. We don't know anything other than the angle between the two, but again, it doesn't appear important given the question.

8. agent0smith

As long as we have the two vectors with an angle 94 deg between them, that's all the question asks.

9. punnus

well @agent0smith you are correct but all I am saying that the first line of the question states that "Make a sketch to show the given vectors" . Though one vector has been defined in term of the other vector but there is not info regarding the other vector and there has to be some reference point from where we measure the vectors direction even if it not asked in the question..

10. agent0smith

^ that just makes any number of sketches valid answers.

11. punnus

And Shall i remin you that is a vector and so both direction and magnitude must be defined @agent0smith

12. punnus

All i want to say the question is incomplete or some information is missing.

13. agent0smith

It doesn't have to be incomplete. The question just wants the student to demonstrate that they understand the angle between two vectors. Yes, vectors should have a given direction, but here... they don't, other than relative to one another.

14. punnus

Then what we can do is to assume a datum line for any general case and solve for it..

15. mathaterme2

So there isn't a way from the question (which I have typed in full all that I was given) to determine the direction of the vectors, right? Only the actual 94 degrees between them would be important? & thanks.

16. agent0smith

^ correct. Even if the direction of the 342 was given, that still doesn't give the actual position of the other vector w/o more information (eg. that they're in the same plane) because the other vector could be going into or out of the page and still be at a 94 deg angle to the first.

17. mathaterme2

Thank you!