Calculating Power and Energy Consumption of Two Coffee-Makers

[Humbleness]

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?

 

[gneill]

Are the coffee makers somehow connected in series? If they are standard appliances, won't they each have to run on 120 V?

 

[Humbleness]

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

 

[gneill]

Yes!

 

[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

 

[kuruman]

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.

 

[Humbleness]

Thank you for your help, I understand now!