-0.5 and -1

[rakuenso]

hi a question:

 

is -0.5 half as large as -1, or is -0.5 twice as large as -1

 

this came up on our physics test...

 

since -0.5 > -1, meaning -0.5 that its larger than -1, so saying something that's half as large would imply that its smaller? which clearly isn't the case....

[the tree]

[math]-0.5\times 2=-1[/math]

[Royston]

Negative and positive numbers are analogous..if you remember that it's hard to slip up.

 

EDIT: Quick note, as a physics question, -0.5 is greater than -1 with regards to temperature. So from a physics perspective, it's kind of a trick question.

[rakuenso]

this is actually the result of a physics question:

 

where the potential V=k(-q)/R

 

conceptually speaking, the potential of a negative charge should increase as the radius increases

[YT2095]

(A) the same, would be my answer.

[Connor]

I would say half as large, and not take the negative into account, as you would divide by two

[rakuenso]

(A) the same, would be my answer.

 

 

the potential is a property of the SOURCE charge, the fact that there's a test charge is irrelevant

 

 

also connor, imagine this:

 

 

source

(-)0V----------------x---------y

 

Point Y would have a bigger potential than X, so it can't be half

[YT2095]

for this example the -q may as well be Zero potential with + and _ charge applied.

and so 2 times the charge over twice the distance will be the same overall potential as half the charge over half the distance regardless of polarity.

[Connor]

for this example the -q may as well be Zero potential with + and _ charge applied.

and so 2 times the charge over twice the distance will be the same overall potential as half the charge over half the distance regardless of polarity.

 

 

but a distance of 2x reduces potential 4x, doesn't it?

[YT2095]

isn`t the distance between charges also Resistance (maybe air or vacuum or even a solid spacer)

so if you assign real values to these points such as Case 1: 1 volt across 1 ohm

and case 2: 2 volts across 2 ohms

 

in both instances 1 Amp is used, so both are the same potential.

 

 

that`s at least how I read the problem

[rakuenso]

can someone move this to the physics forum so we can have the physics experts' opinions?

[Klaynos]

How I'd see this as a physicist...

 

-0.5 and -1 can be considered to be vectors

 

There compareing them as bigger or smaller than the other you would have to compare the moduluses of them which are 0.5 and 1, therefore -1 is two times bigger than -0.5. As the vector is twice as long....

[YT2095]

can someone move this to the physics forum so we can have the physics experts' opinions?

 

I`ve put it in here for now, no other physics area seemed suitable, feel free to let one of us know it you think it`s better somewhere else though.

[J.branco]

as you said before the potencial is a caracteristic of the source charge right?

so being the distance double, the potencial of the second charge is a quarter of the first (2r)^2=4r. So supposing the potencial of the first is -1, the other's will be-1/4. Now -1/4 is bigger than -1 but |-1| is bigger than |-1/4| so i'm not sure. Would choose between D and E.

Being the signals only a case of convention, I would choose D.

[rakuenso]

just so you guys know, the right answer is either B or C

[uncool]

Electric potential is going to be positive anyway, so I would say C) Half as large.

[J.branco]

just so you guys know, the right answer is either B or C

 

yeah sorry. mixed the expressions

 

Just shoot me and rape my skull!