Find the time needed to warm the water to a temperature

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SUMMARY

The discussion focuses on calculating the time required to heat 10 liters of water from 20°C to 120°C using a 1 kW electrical resistance. The relevant equation for this calculation is A = P * t, where A represents the energy required, P is the power, and t is the time. Participants clarify the need to determine the energy required to heat the water, emphasizing the importance of understanding the relationship between power, energy, and temperature change. The conversation also highlights the significance of the system's conditions, such as whether the container is closed or open.

PREREQUISITES
  • Understanding of basic thermodynamics, specifically heat transfer.
  • Familiarity with the equation A = P * t for energy calculations.
  • Knowledge of specific heat capacity of water.
  • Basic principles of pressure and temperature relationships in fluids.
NEXT STEPS
  • Research the specific heat capacity of water to calculate energy requirements.
  • Learn how to apply the formula Q = mcΔT for heat transfer calculations.
  • Explore the effects of pressure on boiling points and heating in closed vs. open systems.
  • Investigate practical applications of electrical resistance heating in real-world scenarios.
USEFUL FOR

Students studying physics, engineers involved in thermal systems, and anyone interested in practical applications of heat transfer principles.

MaiteB
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Homework Statement


An electrical resistance has a power of 1 kW. It is put inside a container that has 10 liters water. The water is in temperature 20C with pressure 1 atm. Find the time to warm the water to the temperature 120C

Homework Equations


A=P*t

The Attempt at a Solution


I thought to use the equation p1/T1=p2/T2 and t=P/A. How can i find A?
 
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Hello MB,

Well, if A is P*t, then writing t = P/A seems a little strange !

So perhaps you can shed a little light here ? First of all, what are these symbols representing ? And their dimensions ?

Warming up water takes heat, energy. The more energy per unit of time (a.k.a. power), the faster it goes.

Furthermore, they tell you the 10 liters of water are at a temperature of 20 ##^\circ##C in a container at a pressure of 1 atm. They don't tell you if the container is closed and kept at a constant volume, or if it's open. In other words, what happens at a temperature of, say, 100 ##^\circ##C :rolleyes: ?

[edit]Oh, and your thread will soon be moved to the introductory physics section by the good spirits that watch over PF
-
 
Last edited:
MaiteB said:

Homework Statement


An electrical resistance has a power of 1 kW. It is put inside a container that has 10 liters water. The water is in temperature 20C with pressure 1 atm. Find the time to warm the water to the temperature 120C

Homework Equations


A=P*t

The Attempt at a Solution


I thought to use the equation p1/T1=p2/T2 and t=A/P. How can i find A?
I corrected it. t-time, A-work, P-power
 
Good (although I don't see it anywhere).
What about the p1T1 = p2T2 ? what are they ?
Can you write an equation to calculate how much energy is needed to heat up 10 liters of water by one degree C ?
 

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