(adsbygoogle = window.adsbygoogle || []).push({}); 1. An object with a charge of -3.6uC and a mass of .012kg experiences an upward electric force, due to a uniform electric field, equal in magnitude to its weight. (a) Find the direction and magnitude of the electric field. (b) If the electric charge on the object is doubled while its mass remains the same, find the direction and magnitude of its acceleration.

2. E=kQ/r(sqrd)

k=8.99 x 10^9 N*m^2/C^2

magnitude of electron's charge (e): 1.60 x 10 ^ -19 C

3. Attempt

W=mg

W= (.012kg)(10)

W=.12N

Upward force equal to magnitude in weight so...

W= W=kQ/r(sqrd)

.12N + (8.99 x 10^9) [(-3.6uC)(1.6 x 10^-19])/(r^2)

Solve for r

r=-431.52

Plug r into E equation to find electric charge.

E=kQ/r(sqrd)

E=(8.99 x 10^9) [(-3.6uC)(1.6 x 10^-9)]/(-431.52^2)

E= -51.7824/-431.52^2

E= -2.78 x 10 ^ -4

I have no idea about part b. Is it always equal to gravity? Is that how they found the answer.

Correct answer from book:

a)(-3.3 x 10^4 N/C) y direction

b)(9.81 m/s^2) y direction

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Uniform Electric Field Upward Electric Force Equals Weight. HELP

**Physics Forums | Science Articles, Homework Help, Discussion**