Solving Statics Questions: Radio Tower, Fw, Fv, Fh

[eurekameh]

http://imageshack.us/photo/my-images/217/unledsdb.png/
So in the picture, we have a radio tower supported by a cable. W is the weight of the radio tower, Fw is the force of the wind, and T is the tension from the cable.

I want to clarify if Fv (a vertical force) is also the normal force on the tower from the floor.
I also want to ask why there is Fh, a horizontal force on the tower from the floor. Is this Fh a force of friction because the tower has an impending motion?

 

[Studiot]

F_v is the vertical reaction of the ground on the antenna mast.

F_h is the horizontal reaction of the ground on the antenna mast.
It would be foolish to leave this to friction rather than a positive fixing at the foot of the mast.
If you think about it, it is the only horizontal force available to balance the horisontal component of the cable tension, if the wind does not blow.
I would hazard a guess that when F_h is calculated it turns out to be negative, since it appears (to me) to point in the wrong direction.

go well

 

[eurekameh]

F_v is the vertical reaction of the ground on the antenna mast.

F_h is the horizontal reaction of the ground on the antenna mast.
It would be foolish to leave this to friction rather than a positive fixing at the foot of the mast.
If you think about it, it is the only horizontal force available to balance the horisontal component of the cable tension, if the wind does not blow.
I would hazard a guess that when F_h is calculated it turns out to be negative, since it appears (to me) to point in the wrong direction.

go well

Fh is negative, so it does point in the opposite direction. But what I'm really asking is, what is causing this vertical / horizontal force on the tower / antenna mast(?) ?
Can we just say that it's a vertical / horizontal force on the tower from the floor? Or can we be more specific in saying that the vertical force is the normal force on the tower from the floor and that the horizontal force is a frictional force?
I'm not understanding "It would be foolish to leave this to friction rather than a positive fixing at the foot of the mast."

 

[Studiot]

I don't know you background but if you push (or pull) against something and it does not move it pushes back at you with equal force.

This return push is called the reaction or reactive force.

So when you stand on the ground you push down on the ground with your weight and the ground pushes back up on you with an equal and opposite reaction so you do not sink into the ground.

That is a vertical reaction.

Similarly if you push horizontally against a wall, it pushes back with an equal and opposite horizontal reaction force.

Since there are horizontal forces acting in your diagram, there must be a horizontal reaction.
This may be provided by friction or it may be because the base is spiked into the ground. It does not matter which, the force must be there or the base of the tower will move.

I simply observed that only a fool would rely on friction being strong enough in such a situation. There is no magic in this.