Electric Force Between +2.8 µC & -4.8 µC: Calculate Now

[gotpink74]

Homework Statement

What is the electric force between a glass ball that has +2.8 µC of charge and a rubber ball that has -4.8 µC of charge when they are separated by a distance of 4.5 cm?

Homework Equations

F=k*Q1*Q2/r^2

The Attempt at a Solution

-59.6507
-8.8888888.889
4.4380e12

 

[gotpink74]

is K 9*10^9

 

[iRaid]

is K 9*10^9

Yes.

 

[gotpink74]

i got -59.7333 but it is still wrong i do not know what i am doing wrong

 

[Redbelly98]

i got -59.7333 but it is still wrong i do not know what i am doing wrong

Please show your work.

 

[gotpink74]

(9*10^9)*(2.8*10^(-6))*(-4.8*10^(-6))/0.045^2

 

[Crwth]

Are you using UTexas Quest? If so, does it give you a value for k? The rounding difference might make your answer a bit off.

 

[Redbelly98]

Usually they just want the magnitude of the force for this type of question. Try without the minus sign, otherwise it looks good to me. You should probably not go more precise than 3 significant figures too.