## butterflyprincess 3 years ago QUICK QUESTION!!** PIC INCLUDED* Suppose that a box is being towed up an inclined plane as shown in the figure. Find the force w needed to make the component of the force parallel to the inclined plane equal to 2.5 lb. Give answer in component form.

1. redshift

We will need that figure to know exactly what is being asked.

2. butterflyprincess

Here is a picture!

3. butterflyprincess

Does anyone know how to solve it D=

4. TuringTest

|dw:1352583686628:dw|

5. TuringTest

|dw:1352583791078:dw|

6. TuringTest

the component parallel to the plane is the magnitude of the force W time the cosine of the angle between the force and the plane, which is 30-15=15degrees

7. butterflyprincess

Wait but the angle given says 33 degrees?

8. TuringTest

sorry, good eye

9. TuringTest

|dw:1352584030549:dw|

10. butterflyprincess

ohokkk

11. butterflyprincess

but how would you get the component form..... like what exactly do i solve for? w?

12. TuringTest

yes

13. butterflyprincess

mhm, okay but how do you know what you have to minus 33 with 15?

14. TuringTest

we want the angle between the ramp and the force the ramp is at an angle of 15 deg to the horizontal the force is at an angle of 33 deg to the horizontal therefore the angle between the force and the ramp is 33-15deg

15. butterflyprincess

Oh okay cool, so how can you set it up to get W?cos 18 = 2.5lbs/w..?

16. TuringTest

start with cos(theta)=F/W where F is the component parallel to the plane we set theta=18 and F=2.5 now yuo can solve for W

17. TuringTest

cuz it's a right triangle...|dw:1352584629296:dw|

18. TuringTest

19. butterflyprincess

ohh Okay so W=2.63/

20. TuringTest

I dunno, let me find a calculator...

21. butterflyprincess

lol ok

22. TuringTest

yep, I get the same :)

23. butterflyprincess

oh okay but the answer says in the book <2.20,1.43> so how can i get there?

24. TuringTest

those must be the *components* of W, so it is W*cos(phi) W*sin(phi) where phi is the angle that W makes with the horizontal

25. TuringTest

|dw:1352585011969:dw|here my exaggerated drawing doesn't work so well :P but Wx and Wy are the x and y components respectively

26. butterflyprincess

what so youd get like (2.62 cos (18) , 2.62 sin (18)?

27. butterflyprincess

D:

28. TuringTest

18 is not the angle that W makes with the horizontal...

29. butterflyprincess

wait really then what would it be?O: