Answer to Question #314630 in Classical Mechanics for umar

Question

A 1.00-g cork ball with charge 2.00 *C is

suspended vertically on a 0.500-m-long light string in the

presence of a uniform, downward-directed electric field of

magnitude E ! 1.00 & 105 N/C. If the ball is displaced

slightly from the vertical, it oscillates like a simple pendulum.

(a) Determine the period of this oscillation.

(b) Should gravity be included in the calculation for part

(a)? Explain.

Answer 1

$T=2\pi\sqrt{\frac la}=2\pi\sqrt{\frac{ml}{mg+F}}=2\pi\sqrt{\frac{ml}{mg+qE}}\approx \sqrt{\frac{ml}{qE}}=5~s.$

$mg\ll qE,$ gravity won't be included in the calculation.