Two tiny conducting spheres are identical and carry charges of -21.6 mC and +51.4 mC. They are separated by a distance of 2.43 cm. What is the magnitude of the force that each sphere experiences?
The "m" in -21.6 mC is "milli" or "micro?" (It reads as "milli" so I don't know if you have that right or not.)
Also the radius is in cm, not m, so the radius squared is $\displaystyle (2.43 \times 10^{-2}~m)^2 = 0.00059049~m^2$
Finally you forgot the constant out at the front: $\displaystyle k = 9 \times 10^9 Nm^2/C^2$.
-Dan
when i multiplied the constant by the remaining number (after fixing my cm to m) I came up with 15246...
which I'm fairly confident is incorrect....
I don't know why I keep getting the wrong numbers...I am also unsure of how to label my answer..that is if I ever figure it out...
I don't know why your calculator isn't working either. This is just "plug-n-chug" stuff.
$\displaystyle F = \frac{(9 \times 10^9)(-21.6 \times 10^{-6})(51.4 \times 10^{-6})}{(2.43 \times 10^{-2})^2} = -194400$
As to the units:
k has a unit of $\displaystyle \frac{Nm^2}{C^2}$
each charge has a unit of C
and r has a unit of m.
Thus F has units of
$\displaystyle \frac{\frac{Nm^2}{C^2} \cdot C \cdot C}{m^2} = N$
as we expect, since F is a force.
-Dan
okay,
so I tried it yet again... just calculating numbers... I used your setup that you have posted here....
I came up with -16968.81 N
Is it possible that this could be the answer?? Or am I still missing something somewhere with my calculations?
I'm not going to plug in the answer to the site until I'm more confident, because I really can't afford to lose the points...