Potential energy and electrostatics

[Bond03]

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According to my book for a proton to move from a surface that is - to a surface that is +, it is going to a higher potential energy and the change in potential energy is negative.

HUH?

 

[Anotherface]

According to my book for a proton to move from a surface that is - to a surface that is +, it is going to a higher potential energy and the change in potential energy is negative.

HUH?

A proton (+) should move towards - (F=kq1q2/r^2). delta(PE)= F* x= integral (kq1q2/r)

If you do the math, you get a negative number

 

[Charles English]

According to my book for a proton to move from a surface that is - to a surface that is +, it is going to a higher potential energy and the change in potential energy is negative.

HUH?

right. another way to think of it is that the proton would rather hang out with the (-) than the (+). more stable = lower potential energy, less stable (i.e. towards the (+)) = higher potential energy

the sign is negative because the force and the displacement are antiparallel (cos180)

the above is right though...if you do the math, thinking about work and PE, it works out. ooh <-- get it 'it works out' /badpun

 

[LaCasta]

Wouldn't the change in potential energy be positive and the work would be negative?

Delta PE = q*delta potential

So if it is moving from an area of lower potential to higher potential then the delta potential term would be positive, and since the charge (q) is positive, this would be positive term.

The work however is W = -deltaPE, so the work is negative

 

[futuredoctor10]

I agree LaCasta:

for a proton to move from a surface that is - to a surface that is +, it is going to a higher potential energy and the change in potential energy is negative.

The proton does not want to move to the + surface.

It is going to a higher potential energy (less stable +)

change in PE - final - initial = high - low = +

So I think the delta PE / change in PE is positive.

W = - delta PE, so work is negative..