We develop a simple model to investigate the orientation-dependence of the drag force acting on a magnet falling inside a vertical conducting pipe. We approximate the magnet by a point magnet and the pipe by a two-dimensional cylindrical surface. Independent of the magnet's orientation, the drag force is proportional to its velocity: . We show that the coefficient of the horizontally oriented magnet is about 2/3 of the coefficient for the vertically oriented magnet. If the magnetic moment makes an angle θ with the vertical direction, the drag coefficient k can be expressed as . When the magnet falls with a non-vertical orientation, a local charge distribution is induced in the pipe, which plays a role as important as that of the time-varying magnetic field due to the falling magnet in generating the eddy currents. The model's predictions are compared with experimental results.
Skip Nav Destination
A magnet falling inside a conducting pipe: Dependence of the drag force on
the magnet orientation
Article navigation
June 2023
PAPERS|
June 01 2023
A magnet falling inside a conducting pipe: Dependence of the drag force on
the magnet orientation
Chang Hyeon Lee
;
Chang Hyeon Lee
a)
Department of Physics, Chungnam National University
, Daejeon
34134, South Korea
Search for other works by this author on:
Byung-Yoon Park
Byung-Yoon Park
b)
Department of Physics, Chungnam National University
, Daejeon
34134, South Korea
Search for other works by this author on:
a)
Electronic mail: [email protected], ORCID: 0000-0001-8843-0221.
b)
Electronic mail: [email protected], ORCID: 0000-0002-6508-7560.
Am. J. Phys. 91, 440–448 (2023)
Article history
Received:
July 09 2021
Accepted:
March 28 2023
Citation
Chang Hyeon Lee, Byung-Yoon Park; A magnet falling inside a conducting pipe: Dependence of the drag force on the magnet orientation. Am. J. Phys. 1 June 2023; 91 (6): 440–448. https://doi.org/10.1119/5.0062860
Download citation file:
Pay-Per-View Access
$40.00
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
879
Views
Citing articles via
Ergodic Lagrangian dynamics in a superhero universe
I. L. Tregillis, George R. R. Martin
All objects and some questions
Charles H. Lineweaver, Vihan M. Patel
The most efficient thermodynamic cycle under general engine constraints
Christopher Ong, Shaun Quek
A story with twists and turns: How to control the rotation of the notched stick
Martin Luttmann, Michel Luttmann
The spinorial ball: A macroscopic object of spin-1/2
Samuel Bernard-Bernardet, Emily Dumas, et al.
In this issue: January 2025
Joanna Behrman, Pierre-François Cohadon, et al.
Related Content
Weighing a Magnet as it Falls with Terminal Velocity Through an Aluminum Pipe
Phys. Teach. (October 2018)
Electromagnetic braking revisited with a magnetic point dipole model
Am. J. Phys. (April 2016)
Damped fall of magnets inside a conducting pipe
Am. J. Phys. (February 2011)
Motion of a falling object retarded by magnetic impulses
Am. J. Phys. (June 2017)
Magnet traveling through a conducting pipe: A variation on the analytical approach
Am. J. Phys. (April 2014)