Answer:
The coefficient of kinetic friction is found to be 0.432.
Explanation:
Comprehensive steps and derivations with necessary substitutions are detailed in the attached document.
A rear window defroster consists of a long, flat wire bonded to the inside surface of the window. When current passes through th
2 answers:
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Part 1) Which metal will cool the fastest?
To determine this, we need to consider the heat flow rate formula, which indicates the speed at which a substance can gain or lose heat:
where:
denotes the heat exchanged
indicates the duration
k represents the thermal conductivity of the material
A is the area over which heat transfer takes place
shows the change in temperature
x is the thickness of the substance
It is evident that the heat flow rate
is directly related to k, the thermal conductivity. Thus, a higher value of k means that the metal will cool more quickly.
Upon examining the thermal conductivity values for each metal, we observe:
- Aluminium: 237 W/(mK)
- Copper: 401 W/(mK)
- Gold: 314 W/(mK)
- Platinum: 69 W/(mK)
Consequently, copper has the highest heat flow rate, making it the metal that cools the fastest.
Part 2) Which sample of copper demonstrates the greatest increase in temperature
To address this part, we can examine how the heat exchanged Q correlates with temperature increase:
where m indicates the mass and Cs represents the specific heat capacity of the material. By rearranging the equation, we derive
As a result, it becomes clear that the temperature increase is inversely related to the mass m. Thus, the block exhibiting the highest temperature rise will be the one with the least mass, hence the right choice is A) 0.5 kg.
To determine this, we need to consider the heat flow rate formula, which indicates the speed at which a substance can gain or lose heat:
where:
k represents the thermal conductivity of the material
A is the area over which heat transfer takes place
x is the thickness of the substance
It is evident that the heat flow rate
Upon examining the thermal conductivity values for each metal, we observe:
- Aluminium: 237 W/(mK)
- Copper: 401 W/(mK)
- Gold: 314 W/(mK)
- Platinum: 69 W/(mK)
Consequently, copper has the highest heat flow rate, making it the metal that cools the fastest.
Part 2) Which sample of copper demonstrates the greatest increase in temperature
To address this part, we can examine how the heat exchanged Q correlates with temperature increase
where m indicates the mass and Cs represents the specific heat capacity of the material. By rearranging the equation, we derive
As a result, it becomes clear that the temperature increase is inversely related to the mass m. Thus, the block exhibiting the highest temperature rise will be the one with the least mass, hence the right choice is A) 0.5 kg.