Solve Electric Field Problem: Find q1 and q2

[NickPA]

Two point charges q1 and q2 are held in place 4.50 cm apart. Another point charge -1.75 mC of mass 4.50 g is initially located 3.00 cm from each of these charges (the figure ) and released from rest. You observe that the initial acceleration of -1.75 mC is 324 m/s^2 upward, parallel to the line connecting the two point charges

Find q1 and q2 ?

I attached a pic of my work.

 

[TSny]

Hello NickPA. Welcome to PF!

Your method of solution looks good. But I don't agree with your value of the angle ø. Also, in the problem statement the mass is given as 4.50 g whereas in your calculation you use 5.00 g. In the statement of the problem, Q is given in mC whereas in your calculation you use μC.

 

[NickPA]

it is supposed to be 5 g. Bad copy and paste sorry. That seems to be the difference between my answer and the right answer. They (the book authors) are using cos, while i used sin, but should it not work?

 

[TSny]

I don't see how you got 41.3 degrees for the angle $\phi$ shown in your figure. Can you show your work here?