## TrojanPoem one year ago Tag

1. TrojanPoem

|dw:1444135482286:dw| if F = 60 n, U = 300 n, theta = 40

2. TrojanPoem

V = 112.7 / 145.9 / 154.3 / 257.9 alpha = 131.4 / 98.6 / 41.4 / 115.2

3. dan815

n?

4. TrojanPoem

Newton

5. dan815

whats with all the V and alpha

6. TrojanPoem

F is the resultat of both V, u

7. phi

I assume you are adding the vectors u and f, and the resultant is v ?

8. dan815

|dw:1444135771546:dw|

9. dan815

arrows here?

10. TrojanPoem

The action direction

11. TrojanPoem

Right.

12. dan815

=.=

13. phi

ok u + V= F |dw:1444135779512:dw|

14. phi

you could use Law of Cosines to find |V| and Law of Sines to find the supplementary angle

15. TrojanPoem

I tried 60 / Sin ( alpha + 40 ) = 300/ sin alpha = v / sin40 I ended up with tan alpha = -1.1

16. phi

law of cos gives 256.9 for | v|

17. dan815

|dw:1444136003702:dw|

18. TrojanPoem

Oh, you used the force triangle for the cosine rule, I used Resultant = v^2 + u ^2 + 2 vu cos apha + theta

19. dan815

or just do vector addition since u are learning vectors

20. TrojanPoem

|dw:1444136349451:dw| Where is f ?

21. TrojanPoem

@phi, your method works , I will continue and see thanks.

22. dan815

u=<300,0> f=<60 cos(40),60 sin (40) v=<x,y> u+v=f 300+x= 60 cos(40) 0+y=60sin(40)

23. phi

alpha, by law of sins is 131.4 |dw:1444136394450:dw|

24. TrojanPoem

@dan815 , Never thought I could use vectors like this nice nice

25. dan815

ya vectors make it neat ^^

26. TrojanPoem

Thanks @phi, @dan815

27. TrojanPoem

medal to who ?

28. phi

you can also you components. u+v= f so v= f-u f=<300,0> (we let f point along the x-axis u= 60<cos 40, -sin 40> v= <60 cos(40) - 300, -60 sin(40) > now find the magnitude and angle of v |v| = 256.9 angle = atan(y/x) = 8.6 deg in the 3rd quadrant= 171.4 alpha = 171.4-40= 131.4 deg

29. dan815

lol