# Determine the speed of the rod after it has traveled 2.50 m

An insulating rod having linear charge density λ = 14.0 µC/m and linear mass density μ = 0.100 kg/m is released from rest in a uniform electric field E = 65 V/m directed perpendicular to the rod.

(a) Determine the speed of the rod after it has traveled 2.50 m.
m/s

(b) How does your answer to part (a) change if the electric field is not perpendicular to the rod?

Explain.

asked Jan 20, 2012 in Physics

Part A:

First arbitrarily take V = 0 at point P.  Then at the distance d downward, where L is the rod length you have that

V = -Ed

and hence,

U = -λ*L*E*d

Now insert these components into the conservation of energy equation which is

Ki + Ui = Kf + Uf

substitute in components to get

0 + 0 = (1/2)*μ*L*v^2 - λ*L*E*d

solving for v you get that,

v = square root of (2* λ*L*E*d / μ)

Now plug in your values given in the equation, remember to convert the units to SI units, and the answer should be:

v = 0.2133 m/s

Part B: it stays the same

answered Jan 25, 2012 by ~Expert~ (3,020 points)
selected Jan 28, 2012 by awesome