Physics question (electricity poles) a 9-th grader question :D

[Mister Darius]

I'm participating in this thing which can't be translated (I'm not sure about it) and it has this question, which even my physics teacher don't know the answer for. I will try to do my best at translating and explaining it.

Here's the pic:


And the mediocre translation:

Why is the insulator hook bent so that its axis passes through the screw cable. I hope you get it.

 

[Ironsounds]

Hello... 1) Could be for experiments with different insulators, this position with gravity, was the most practical mounting.
2) in Older drawing's, before CAD, showing a "axis" line... helps to visualize an hand drawn idea.
3) The shape of the mounting ( typically metal ) will also increase the distance and electrical insulation from the HOT wire to ground.

 

[kanewolf]

My answer has nothing to do with electricity, I believe it is so that there is no surface area which could accumulate water and lower the resistance. The area that can accumulate water still has an air gap to the metal part. If the screw was straight the insulator would have a large horizontal surface which would have a lower resistance with a layer of water. Same concept as putting a "drip loop" in a cable. It gives water a place to drip from an not accumulate.

 

[ex_bubblehead]

The large "U" also allows for flex, and reduces the tension on the threads holding the bracket to the (wall, pole, etc.), thus less likely to rip out.

 

[Mister Darius]

Thanks for all the answers, but none actually answered the thing which I really need to know (unless I missed it somewhere in your answers)

1 is in level with the 2, that is what I need to know why it is like that. I really can't explain it better 'cause of my limited English

 

[ex_bubblehead]

Make 3 drawings:

1. As currently drawn

Then, without changing the left hand side of the "U":

2. Extend "2" higher
3. Extend "2" lower

Now pull "2" straight out parallel to the red line you drew above.

Which one puts the tension directly in line with the drawn axis?

 

[Mister Darius]

Make 3 drawings:

1. As currently drawn

Then, without changing the left hand side of the "U":

2. Extend "2" higher
3. Extend "2" lower

Now pull "2" straight out parallel to the red line you drew above.

Which one puts the tension directly in line with the drawn axis?

If I understand you correctly (my english is pretty bad in terms of physic terms) then pulling the isolator parralel to the red line would put the tension directly in line with the axis

 

[ex_bubblehead]

Draw your force vectors for each instance, the answer will reveal itself 😉

 

[Mister Darius]

Draw your force vectors for each instance, the answer will reveal itself 😉

I will try to explain myself one more time, because im not sure if you understood me correctly.

The question is why the isolator is in the same level as the hooks axis (the red line) and not higher than the hooks axis or lower (something with the center of mass maybe). To answer this question it shouldn't require force vectors, because we don't know them yet.

 

[ex_bubblehead]

I understood you perfectly well. I'm avoiding simply giving you an answer as that would teach you nothing. If you do as I say above you will find the answer (fairly quickly too)

 

[Mister Darius]

I understood you perfectly well. I'm avoiding simply giving you an answer as that would teach you nothing. If you do as I say above you will find the answer (fairly quickly too)

Yeah, but none of the 20 questions I got require force vectors, because they are mostly still from the 8grade and they pretty much require knowledge about ramps, something about pressure and density.

The one Im needing help for only would need text explanation. I only have to answer why the people building these isolators bend the hooks so they would be at the same height as its thing screweng into the pole.


.....Or you are actually giving me the right answer, but I dont even know force vectors and how would I draw them in this body, idk,

 

[ex_bubblehead]

It's a dead simple mechanical question, involving levers:

What happens to the hook at the point it enters the wall/pole if a force is applied parallel to the drawn axis if the insulator is:

1. Above the point of entry
2. Even with the point of entry
3. Below the point of entry

Once you have those answers the reason for the design will be self evident.

 

[Ralston18]

Plus, with respect to ex_bubblehead's "What happens" question, expand your thinking to consider the initial installation, repairs/replacement, and the effect of the supported wire being pulled or weighted down?

Remember that most likely there will be a string of poles and insulators supporting the wire for some distance. Exposed to hot, cold, wind, ice....

The "U" design actually addresses a variety of issues or potential problems some of which have been commented on.

Your initial "why" is actually one of those fun questions that has both technical (forces, vectors, torque) and practical answers.