Calculating Power and Energy Consumption of Two Coffee-Makers

  • Thread starter Thread starter Humbleness
  • Start date Start date
  • Tags Tags
    Energy Power
Click For Summary

Homework Help Overview

The discussion revolves around calculating the power and energy consumption of two coffee-makers connected to a 120V power supply. The problem involves understanding the electrical principles related to power and energy, specifically in the context of resistive loads.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants explore the configuration of the coffee-makers, questioning whether they are connected in series or parallel. There are attempts to calculate power using the formula P=V²/R, with varying interpretations of the total energy consumption based on the operation time of each coffee-maker.

Discussion Status

Multiple interpretations of the problem are being explored, particularly regarding the operation time of the coffee-makers and how it affects total energy consumption. Some participants have provided calculations, while others seek clarification on the assumptions made in the problem setup.

Contextual Notes

There is some confusion regarding the total operational time for the coffee-makers, with discussions on whether the time should be considered separately for each appliance or combined. This uncertainty affects the calculations of energy consumption.

Humbleness
Messages
31
Reaction score
1

Homework Statement


Two 15Ω coffee-makers are connected to a 120V power supply for two hours a day each. Find the power and energy.

Homework Equations


P=V2/R
ΔE=PΔt

The Attempt at a Solution


I am assuming, since there are two coffee-makers connected to one 120V power supply, that:
P = V2/R = 1202V/30Ω = 480W or 0.48kW

ΔE = PΔt = 0.48 kW x 2h = 0.96 kWh

Can someone confirm?
 
Physics news on Phys.org
Are the coffee makers somehow connected in series? If they are standard appliances, won't they each have to run on 120 V?
 
  • Like
Likes   Reactions: Humbleness
gneill said:
Are the coffee makers somehow connected in series? If they are standard appliances, won't they each have to run on 120 V?
Hmm makes sense. Therefore,
P = V2 / R = 1202 / 15 = 960 W or 0.96 kW
Then I would multiply this by 2, since there are two coffee-makers?
0.96 x 2 = 1.92 kW

ΔE = PΔt = 1.92 kW x 2h = 3.84 kWh
 
Yes! :smile:
 
  • Like
Likes   Reactions: Humbleness
I am confused over the 2 hours each though...
Would that mean that one coffee-maker runs on 120 V for 2 hours, as well as the second?
So my total time should actually be 4h?
ΔE = PΔt = 1.92 kW x 4h = 7.68 kWh
 
One coffee maker running for four hours consumes as much power as two coffee makers running for 2 hours.

On edit: Oops, I made a mistake. I meant to say that one coffee maker running for four hours consumes as much energy (not power) as two coffee makers running for 2 hours. :oops:
 
Last edited:
  • Like
Likes   Reactions: Humbleness
Thank you for your help, I understand now! :smile:
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 6 ·
Replies
6
Views
7K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 8 ·
Replies
8
Views
4K
Replies
6
Views
4K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 14 ·
Replies
14
Views
5K