1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: 2 magnets falling, one through a metal ring, which is faster

  1. Nov 2, 2015 #1
    1. The problem statement, all variables and given/known data
    Two small bar magnets X and Y are released from rest at the same height above the ground. X falls directly to the ground, but Y passes through a metal right which is fixed with its plane horizontal. Does X reach the ground: (A) at the same time as Y, (B) before Y, (C) after Y? Explain your answer.

    2. The attempt at a solution
    I think that X will reach the ground before Y because the metal ring will slow down the Y magnet. The Y magnet will be retarded before entering the ring and after passing it. But I don't know whether this is right and what's the cause of it. Electromagnetic induction? The ring should magnetize the magnet on entering and should keep it when it passes through it as I see it.
  2. jcsd
  3. Nov 2, 2015 #2


    User Avatar
    Gold Member

    Before entering and after passing? Nope.
    Correct. Lenz's law is the apt way to put it. When the magnet passes through the metal tube, the magnetic flux relative to the tube changes. The changing flux produces current in the metal tube, in such a way that it opposes the motion of the magnet. :smile:

    Here is a link if you are interested...
  4. Nov 2, 2015 #3


    User Avatar
    Science Advisor
    Gold Member

    If you don't want to run down to the hardware store to buy some pipe, a roll of aluminum foil works great for this experiment.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted