Calculating Time to Melt Substance at 80 C

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SUMMARY

The discussion focuses on calculating the time required to melt a 0.2 kg solid substance at 80°C using a circuit with a 40-ohm resistor connected to a 60 V power supply. The heat of fusion for the substance is specified as 1.35 x 10^5 J/kg. To determine the time to melt the substance, participants are guided to calculate the power delivered by the circuit using the formula P = UI, where U is the voltage and I is the current derived from Ohm's Law. The calculated power will then be used to find the total energy required for melting and subsequently the time needed.

PREREQUISITES
  • Understanding of Ohm's Law and electrical circuits
  • Knowledge of heat transfer concepts, specifically heat of fusion
  • Familiarity with basic physics formulas for power and energy
  • Ability to perform unit conversions and calculations involving Joules and seconds
NEXT STEPS
  • Calculate the power delivered by the circuit using P = UI
  • Determine the total energy required to melt the substance using Q = m * Lf
  • Calculate the time to melt the substance using the formula time = Q / P
  • Explore the implications of varying resistor values on power output and melting time
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Students and professionals in physics, electrical engineering, and thermodynamics who are interested in practical applications of heat transfer and electrical power calculations.

lalala_land89
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a portion of an electirc circuit connected toa 40-ohm resistor is embedded in .2 kg of a solid substance in a calorimeter. The externam portion of the circuit is connected to a 60 V power supply.

At 80 C the substance begins to melt. The heat of fusion of the substance is 1.35*10^5 J/kg. How long after the temperature reaches 80 C will it take to melt all of the substance?

I really don't understand how to find time. I get that there's a way to find heat of fusion, but it's already given to me. help please

i have originally posted this in the advanced physics but no one helped. maybe someone here will.
 
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What is the energy delivered per second to the substance?

Can you find the power of the power supply? (Hint: P=UI and Ohm's Law)
 

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