Finding the E-field of a mass hanging from a string

[aximwolf]

9. [1pt]

As shown in the figure above, a ball of mass 0.480 g and positive charge q =32.7microC is suspended on a string of negligible mass in a uniform electric field. We observe that the ball hangs at an angle of theta=15.0o from the vertical. What is the magnitude of the electric field?

Fx= Fe - Tsin(theta)= 0
Fy= Tcos(theta) = 0

Tsin(theta)/Tcos(theta) = Fe\mg

Than E= Fe/q

So Tan(theta)mg = Fe/q = E

I got (Tan(15)*.480*9.8)/32.7e-6= 3.9 e 4
Where did I go wrong?

 

[gneill]

Note the units in which the mass was specified.

EDIT: Note also that since this is a homework problem, it should have been posted in one of the homework forums, in particular the Introductory Physics Forum.

EDIT by mentor: this thread has been moved to the appropriate location.

 

[aximwolf]

Its right! Thank you for responding so fast!