a few stupid questions

[agill786]

Hi,
I have a really random question that just came up, I saw a TBR passage awhile back about a car that was driving on a flat surface and it said the work the car does on the road is in the form of friction, but I think it also asked what work is being done on the car?

Could work done by gravity be considered here?


Also, with regards to insulators vs. conductors. On one of my old TBR handouts, it said that conductors are better at holding charge...isn't it insulators? Thats what dielectrics are made of, no?

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[gunj122]

work done by gravity is zero here in this case because the car doesn't change its position in the Y-axis. Also note, work is not a state function, so it's dependent on the distance traveled, not the displacement.

Idk about your second question lol.

 

[agill786]

Thanks that helps!

For the second one I think I'm right and I'm gonna go with insulator

 

[RocketSurgeon]

Hmm for your second question what comes to mind is a Van De Graff generator...

when you have a conductor which is not earthed and you keep putting charge on it, it will spread across the surface so you can hold a lot of charge and at the point where you are adding the charge the potential difference is not that large so it is also easier to add charge

BUT

but for an insulator the charge does not travel so it is harder to add charge to it...

also remember a conducting material can be insulated by isolation !