2 questions for Statics class.. can someone help? (if you can handle it)?

Question

A rope is tied to the top of a 10 m flagpole, the rope is tensioned to 120 N, then tied to straight stick in ground 20m from bottom of pole. The ground is level. Find the vertical and horizontal component of force applied at the top of the flagpole.

ALSO

The howv roof truss shown is subjected to wind loads as shown. Wind loads are perpendicular to inclined cords. Resolve each force into vertical and horizontal components.

The wind loads are 2, 4, 2 kilo lbs. And its 12 in. tall and 48 in. across.

Answer 1

For the first question, you can determine the angle the rope makes with the ground (10m high and 20m from the pole). That gives you an angle of roughly 26.57 deg. (or however you want to express it). The rope is pulling both vertically and horizontally on the pole, with a total tension of 120N. So, the vertical component is 120 sin 26.57 and the horizontal component is 120 cos 26.57 You'll see that the horizontal component is twice the vertical component, just the same as the distance from the pole is twice the height.

As for the second question, I am having a hard time picturing exactly what is going on (and it will make it more difficult to explain). I'm assuming the total width of the truss is 48, so you essentially have two 12x24 triangles, with the chords being the hypotenuse of the triangle. Using that assumption, your force is perpendicular to the chord. Try to picture two right triangles on the chord. One is the applied force, half the chord and the horizontal component. The other is the force, half the chord and the vertical component. From the geometry of the chord, you can determine the angle the horizontal and vertical components make with the chord itself. Then you need to solve those two triangles I just described. For one, theforce relationship is F=Fh*sin26.57 and for the other it is F=Fv*sin63.43.

Hope this helps.