# If it starts from rest, what is the speed of the rod as it leaves the rails?

A rod of mass 0.720 kg and radius 6.00 cm rests on two parallel rails (see figure below) that are d = 12.0 cm apart and

L = 45.0 cm long. The rod carries a current of I = 56.0 A in the direction shown and rolls along the rails without slipping. A uniform magnetic field of magnitude 0.400 T is directed perpendicular to the rod and the rails. If it starts from rest, what is the speed of the rod as it leaves the rails? (Assume that the rod is of uniform density.)
m/s

asked Feb 19, 2012 in Physics

Here is the formula you would need to use to solve the problem:

For steps on deriving the formula refer to the link below:

You are given:

I = 56.0 A

B =  0.400 T

L = 45.0 cm = 0.45 m

d = 12 cm = 0.12 m

m = 0.720 kg

plugging these values into the formula above you get:

v = squareroot ((4 * (56.0 A) * (0.12 m) * (0.400 T) * (0.45m)) / (3 * 0.720 kg))

v = 1.497 m/s

answered Feb 23, 2012 by ~Expert~ (3,856 points)
selected Feb 23, 2012 by Joey33