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## anonymous 5 years ago I have a doubt which needs to be urgently solved cause i got a test tommorow!!!!!!!!The question is in the replies cause i cannot write a diagram or attach a diagram here!!!!! Its physics i know its a wrong section to ask at but i have no choice!!!!!!!

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1. anonymous

I want to know how can we find the vertical component of the force vector here for normal reaction using $N _{a}\cos \Theta$ rather than$N_{a}\sin \Theta$

2. watchmath

It depends on where your $$\Theta$$ is

3. anonymous

hang on i am scanning the diagram

4. anonymous

here is the diagram pls answer quickly!!!!!!!!!!

5. anonymous

this fairly easy

6. anonymous

so answer it pls!!!!!!!!!!!!!

7. anonymous

well , just consider the angle between theta1 and the vector mg

8. anonymous

so then!!!!!!!!!!

9. anonymous

this will be 90 - theta

10. anonymous

then do trig in that triangle

11. anonymous

fine!!! further ahead!!!!!!!

12. anonymous

yeh.. im answering it , its just a bit slow lol

13. anonymous

k sorry!!!!!!

14. anonymous

i need to know why is the vertical component of say Na NaCos Theta and not Na sin Theta

15. anonymous

yeh , its basically because sin(90-x) = cos(x)

16. anonymous

lol, thats wrong cos(90-x) = sin(x)

17. anonymous

but is that the triangle we can use to do this cause i don't think so!!!!!!! and now i am confused with the two comments u made

18. anonymous

can any1 make a quick video and attach it i know i am asking way too much but pls do if possible!!!!!!!!

19. anonymous

ill draw a picture on paint , hopefully it will help lol

20. anonymous

k hopefully!!!!!!!!!!!!

21. anonymous

22. anonymous

ill do another one

23. anonymous

24. anonymous

second picture is just redrawing the top triangle in the previous picture, and marking in what you know

25. anonymous

now in the second triganle you apply trig sin( 90-x) = Na / Fy

26. anonymous

but sin(90-x) = cos(x)

27. anonymous

so Fy = Na / cos(x)

28. anonymous

wait dont think thats right

29. anonymous

thanks for ur effort but cud u use a the line tool to make the diagram cause this is really strange i am not able to make sense

30. anonymous

to be honest I dont really know what you are asking , what is the actual question ?

31. anonymous

and if you look at it , the second triangle , the one that has two sides ( one being the y axis and the other being the plane along the track

32. anonymous

that is a right angled trangle , and the angle between the track and the y axis is just 90-theta

33. anonymous

then you re draw the triangle and apply basic trig ratios and simply sin(90-x) to cos(x)

34. anonymous

i am trying to relate it to the concept of vectors which we can represent on the x axis and the y axis!!!!!

35. anonymous

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