- 260

- 0

Hi ^^! I was doing my physics homework and had a little trouble doing this one, so I was wondering if anyone could help me out if they had time. It would mean alot, but thanks anyway just for reading this ^_^!! I appreciate it =)

Two spheres, each having a mass of 50 mg, are suspended from a common point by massless threads 50 cm long. One of the spheres has been given a charge twice that of the other. The strings make an angle of 6 degrees.

What are the charges on each of the spheres?

What kind of charge is on each sphere (+ or -)? Explain

F = kq1q2/r^2

Q = Ne

F = ma

q_1 = 2q_2

Well, assuming that the charges are not coming close together, they must be repelling each other. As such, I thought there must be some kind of acceleration... F = 2ma = 2(50 x 10^-6 kg)(9.8 m/s^2) = 9.8 x 10^-4 N

In addition, if I use sin6 = x/.5m, I can tell the distance separating the charges is .0523 m.

Now that I found the F, I plugged it into the first equation

9.8 x 10^-4 N = (9x10^9)(q_1)(q_2)/(.0523 m^2)

(q_1)(q_2) = 2.978 x 10^-16 C

2q_2^2 = 2.978 x 10^-16 C

q_2 = 1.22 x 10^-8 C

q_1 = 2q_2

q_1 = 2.44 x 10^-8 C

As for the kind of charge, I said that it is impossible to tell except that the must both be either positive or negative, not one and the other, because otherwise there would not be a 6* angle separating them.

**1. Homework Statement**Two spheres, each having a mass of 50 mg, are suspended from a common point by massless threads 50 cm long. One of the spheres has been given a charge twice that of the other. The strings make an angle of 6 degrees.

What are the charges on each of the spheres?

What kind of charge is on each sphere (+ or -)? Explain

**2. Homework Equations**F = kq1q2/r^2

Q = Ne

F = ma

q_1 = 2q_2

**3. The Attempt at a Solution**Well, assuming that the charges are not coming close together, they must be repelling each other. As such, I thought there must be some kind of acceleration... F = 2ma = 2(50 x 10^-6 kg)(9.8 m/s^2) = 9.8 x 10^-4 N

In addition, if I use sin6 = x/.5m, I can tell the distance separating the charges is .0523 m.

Now that I found the F, I plugged it into the first equation

9.8 x 10^-4 N = (9x10^9)(q_1)(q_2)/(.0523 m^2)

(q_1)(q_2) = 2.978 x 10^-16 C

2q_2^2 = 2.978 x 10^-16 C

q_2 = 1.22 x 10^-8 C

q_1 = 2q_2

q_1 = 2.44 x 10^-8 C

As for the kind of charge, I said that it is impossible to tell except that the must both be either positive or negative, not one and the other, because otherwise there would not be a 6* angle separating them.

Last edited: