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Physics 8 Online
OpenStudy (anonymous):

Two charges, QL and QR have the same magnitude of charge. QR is fixed in place as shown in the diagram below. A second charge QL is attached to a massless string which makes an angle of 22.1° with respect to the horizontal. QL is not moving (and not accelerating) and is located d = 0.317 m directly to the left of QR. QL has a mass of 12.5 kg.

OpenStudy (anonymous):

What is the magnitude of the charge on QL (in μC)?

OpenStudy (anonymous):

OpenStudy (anonymous):

180-22.1=157.9 9.8*12.5/sin(157.9)=325.6 325.6*cos(157.9)=-301.68

OpenStudy (anonymous):

Q=sqrt(301.68)*(.317)^2/k=3372138100

OpenStudy (anonymous):

Do i then times by 10^6?

OpenStudy (anonymous):

Since the charge QL is not moving, you need to balance the forces acting on it.

OpenStudy (anonymous):

Im not sure I understand

OpenStudy (anonymous):

|dw:1406061447961:dw|

OpenStudy (anonymous):

Components of T are as |dw:1406061635001:dw|

OpenStudy (anonymous):

Since QL is not moving \(F_g = T sin \theta\) and \(F = T cos \theta\)

OpenStudy (anonymous):

T is not given. So eliminate T by dividing these two equations and you get \(\frac{F_g}{F} = \frac{sin \theta}{cos \theta }\)

OpenStudy (anonymous):

so sin(22.1)/cos(22/1)?

OpenStudy (anonymous):

use calculator for this

OpenStudy (anonymous):

yep I got .406

OpenStudy (anonymous):

Right!

OpenStudy (anonymous):

its due in four minutes lol no pressure but could you help me with the rest?

OpenStudy (anonymous):

Let the charge on QL (or QR) is q, then \( F = k\frac{q^2}{d^2}\) and \(F_g = mg = 12.5 g\) \(\frac{sin 22.1^o}{cos 22.1^o} = tan 22.1^o = 0.406\) Calculate q.

OpenStudy (anonymous):

wait so solve for what?

OpenStudy (anonymous):

Solve for q. Use k = 9*10^9

OpenStudy (anonymous):

whats F?

OpenStudy (anonymous):

Oh crap times gonna run out

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