Question

A small pith ball has charge of +1.50 mC and is tied to a massless string and placed in a 2d Electric Field. If the string has an angle of 30.0° with the vertical and the E field is given as E=2600.i-4850.j N/C, what is the mass of the ball in kg?

Answer 1

Charge q= 1.5mC = 1.5x10-3C

Two dimensional electric field E= 2600$\hat{i}$ - 4850$\hat{j}$ N/C

$\theta$=300

Mass o the ball= ?? in kg

  

* In the above diagram F is the force acting on the charged ball due to electic fileld that dispalces the ball through an angle 300.

* Force F=qE

* As the electric field is two dimensional then the force acting on the charge due to electric field is also two dimessional.

* Therefore F=Fx + Fy

Fx=qEx=(1.5x10-3)(2600)   $\because$ Ex=2600 N/C

Fy=qEy= (1.5x10-3)(4850) $\because$ Ey=4850 N/C

mg Fy- Tamo Tamo + Fy Fox - fly Tamo

1.5x163x2600+ (1.5x163) 24850 m- 10 an 1.5x163x2600153 +1.5x163x2850 10 m - - 1.5X163 (260053 +4850) 10 m=158163 (4503.33424850) m = 1.57163 (9353.3321) m= 14029.99815 8103 m = 14.03kg m = 14kg.

Thus the mass of the ball is 14kg