How Does Polishing Affect Heat Flow in a Gold Ring?

[musicmar]

Homework Statement

You are polishing a 10.0 g gold ring. (treat as an ideal solid). After doing this for a minute, you find that the ring is hot, having increased the temperature by 15 deg C. Calculate the heat that flows into or out of the system and specify which direction.

Homework Equations

ΔE_therm=Q_in+W_on
ΔE_therm=nCΔT
C_ideal=3R

The Attempt at a Solution

nCΔT=Q_in+W_on

I can calculate nCΔT, but I don't know what to do about the work. Once I find the work done, then I can find Q.

 

[Mapes]

Mechanical work can be written as [itex]-P\Delta V[/itex], where P is the pressure and [itex]\Delta V[/itex] is the volume change. Has the ring changed volume?

 

[musicmar]

Not that we know of. So, does that mean that there is no work done, so ΔE_therm=Q_in?

 

[Mapes]

Sure.

 

[rwisz]

As a scientist, we must first understand the concept of heat flow and how it relates to an ideal solid. Heat flow, or thermal energy, is the transfer of energy from a hotter object to a cooler object. In an ideal solid, the particles are tightly packed and have strong bonds, which makes it difficult for heat to flow through the material.

In this scenario, the heat flowing into or out of the system is due to the friction between the polishing cloth and the gold ring. As you polish the ring, the friction creates heat energy, which causes the temperature of the ring to increase. This increase in temperature can be calculated using the equation ΔEtherm=nCΔT, where n is the number of particles, C is the specific heat capacity, and ΔT is the change in temperature.

Since we are treating the gold ring as an ideal solid, we can use the equation Cideal=3R, where R is the gas constant. Therefore, nCΔT=3RΔT.

To calculate the work done, we need to know the force applied and the distance over which it is applied. In this scenario, the force applied is the friction force between the polishing cloth and the ring, and the distance is the distance the cloth moves while polishing the ring. However, since we do not have this information, we cannot accurately calculate the work done.

In conclusion, we can calculate the heat flow into the system, but we cannot accurately calculate the work done. Therefore, we cannot determine the exact direction of heat flow, but we can say that heat is flowing into the system due to the increase in temperature of the gold ring.