Solving Power Equation: Melting an Ice Cube

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Homework Help Overview

The discussion revolves around a problem involving the power equation in the context of melting an ice cube in a microwave oven. The original poster presents a scenario where the power delivered is 135 W and the energy required to melt the ice cube is 33200 Joules, leading to questions about the time it takes to melt the ice.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between power, work, and time, with some questioning the units involved and the interpretation of the power equation. There are attempts to rearrange the equation to solve for time, leading to confusion about the calculations.

Discussion Status

Participants are actively engaging with the problem, clarifying the definitions of power and work. Some have acknowledged misunderstandings in their initial interpretations, while others are providing corrections and insights into the units and relationships involved.

Contextual Notes

There are indications of confusion regarding the units of power and work, as well as the proper application of the power equation. The original poster expresses uncertainty about their calculations and the rearrangement of the equation.

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Power Equation??

Homework Statement



An ice cube is placed in a microwave oven. Suppose the oven delivers 135 W of power to the ice cube and that it takes 33200 Joules to melt it. How long does it take for the ice cube to melt?

Homework Equations



P = W / T

The Attempt at a Solution



Ok so I know the answer but this is confusing me... A unit of Power is J/second. So if we rearrange the equation and solve for T in minutes it would be.

T = W / P,

T = 135 / 33200 which doesn't give us the right equation to solve it...

Instead it would be 33200 / 135 / 60 = 4.1 minutes, But why when I rearrange the equation doesn't it make sense?
 
Last edited:
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33200 of what units? Badly stated question. "135 of power"?

P = W/T ? What do you think P and W represent?
 


lewando said:
33200 of what units? Badly stated question. "135 of power"?

P = W/T ? What do you think P and W represent?

Power = Watts / Time, Fixed my typo up above.

Ugh nvm I just went full retard. I read the question wrong. Ty anyway!
 


Use power = work (or energy) / time. Power has units of Watts.
 


lewando said:
Use power = work (or energy) / time. Power has units of Watts.

Yea that's what confused me... I mixed up watts and work. Ty!
 

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