Solving Heat Energy Dissipation for a Falling Magnet

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Homework Help Overview

The discussion revolves around a physics problem involving a magnet dropped through a copper tube, focusing on the energy dissipation due to eddy currents. Participants are exploring the relationship between potential energy, kinetic energy, and heat energy in this context.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are attempting to calculate the potential energy of the magnet and questioning the implications of this energy loss. There are inquiries about the relationship between the calculated potential energy and the energy dissipated as heat.

Discussion Status

Multiple interpretations of the energy transformations are being explored, particularly regarding the potential energy lost by the magnet and how it relates to the kinetic energy observed as it exits the tube. Some participants are providing insights into the effects of different materials and tube diameters on the magnet's motion.

Contextual Notes

Participants are considering the initial potential energy with respect to the bottom of the tube and questioning what happens to this energy as the magnet falls through the copper tube. There is an emphasis on understanding the energy conversion processes involved.

carpelumen
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Homework Statement


A magnet of mass 0.10 kg is dropped from rest and falls vertically through a 35.0 cm copper tube. Eddy currents are induced, causing the copper to warm up. The speed of the magnet as it emerges from the tube is 1.50 m/s. How much heat energy is dissipated to the environment?

Homework Equations


E = mgh

The Attempt at a Solution


h = 35 cm --> .35 m

E = (.10 kg) * (9.81) * (.35 m) = .3433 J

Is the equation incorrect?
 
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carpelumen said:

Homework Statement


A magnet of mass 0.10 kg is dropped from rest and falls vertically through a 35.0 cm copper tube. Eddy currents are induced, causing the copper to warm up. The speed of the magnet as it emerges from the tube is 1.50 m/s. How much heat energy is dissipated to the environment?

Homework Equations


E = mgh

The Attempt at a Solution


h = 35 cm --> .35 m

E = (.10 kg) * (9.81) * (.35 m) = .3433 J

Is the equation incorrect?

It is the initial energy if you take the potential energy zero at the bottom of the tube. But what is the loss of energy?

ehild
 
carpelumen said:

Homework Statement


A magnet of mass 0.10 kg is dropped from rest and falls vertically through a 35.0 cm copper tube. Eddy currents are induced, causing the copper to warm up. The speed of the magnet as it emerges from the tube is 1.50 m/s. How much heat energy is dissipated to the environment?

Homework Equations


E = mgh

The Attempt at a Solution


h = 35 cm --> .35 m

E = (.10 kg) * (9.81) * (.35 m) = .3433 J

Is the equation incorrect?
What happens to the P.E. that you have just calculated the magnet loses?
 
An illustrative experiment on this issue
 
Jakob Weg said:
An illustrative experiment on this issue

Good! We note that a larger-diameter tube slows the magnet down more than a smaller-diameter one, following emf = -dΦ/dt. Also that Cu slowed the magnet down more than did Al or brass, following i = emf/R. Vielen Dank!
 
carpelumen said:

Homework Statement


A magnet of mass 0.10 kg is dropped from rest and falls vertically through a 35.0 cm copper tube. Eddy currents are induced, causing the copper to warm up. The speed of the magnet as it emerges from the tube is 1.50 m/s. How much heat energy is dissipated to the environment?

Homework Equations


E = mgh

The Attempt at a Solution


h = 35 cm --> .35 m

E = (.10 kg) * (9.81) * (.35 m) = .3433 J

Is the equation incorrect?
That's the kinetic energy (k.e.) that would have developed in the absence of the copper tube. What was the k.e. with the tube?
 

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