Try the fastest way to create flashcards
Question

A refrigerator has a coefficient of performance of 2.25, runs on an input of 135 W of electrical power, and keeps its inside compartment at 5C5^{\circ} \mathrm{C}. If you put a dozen 1.0-L plastic bottles of water at 31C31^{\circ} \mathrm{C} into this refrigerator, how long will it take for them to be cooled down to 5C5^{\circ} \mathrm{C}? (Ignore any heat that leaves the plastic.)

Solutions

Verified
Answered 1 year ago
Step 1
1 of 10

We will solve this problem by using the fact that refrigerator takes heat from inside the refrigerator required for lowering temperature of water in bottles from initial temperature (temperature of water bottles when they are placed inside the refrigerator) to final temperature (temperature inside refrigerator that is kept constant).

We are given:

  • coefficient of performance of refrigerator K=2.25K=2.25 -electrical power input of refrigerator P=135 WP=135 \mathrm{~W}
  • temperature inside the refrigerator Tr=5T_r=5^{\circ}
  • volume of each of the water bottle V=1 LV=1 \mathrm{~L}
  • number of water bottles placed inside the refrigerator N=12N=12 (dozen water bottles)
  • initial temperature of water in water bottles Twb=31T_{wb}=31^{\circ}

We need to know to solve this problem:

  • specific heat capacity of water c=4179 JkgKc=4179 \mathrm{~\tfrac{J}{kg \cdot K}}
  • mass density of water ρ=1000 kgm3\rho=1000 \mathrm{~\tfrac{kg}{m^3}}

Create a free account to view solutions

Create a free account to view solutions

Recommended textbook solutions

Physics for Scientists and Engineers: A Strategic Approach with Modern Physics 4th Edition by Randall D. Knight

Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

4th EditionISBN: 9780133942651 (8 more)Randall D. Knight
3,508 solutions
Sears and Zemansky's University Physics 14th Edition by Hugh D. Young, Roger A. Freedman

Sears and Zemansky's University Physics

14th EditionISBN: 9780133969290Hugh D. Young, Roger A. Freedman
8,575 solutions
Mathematical Methods in the Physical Sciences 3rd Edition by Mary L. Boas

Mathematical Methods in the Physical Sciences

3rd EditionISBN: 9780471198260 (1 more)Mary L. Boas
3,355 solutions
Fundamentals of Physics 10th Edition by David Halliday, Jearl Walker, Robert Resnick

Fundamentals of Physics

10th EditionISBN: 9781118230718 (3 more)David Halliday, Jearl Walker, Robert Resnick
8,971 solutions

More related questions

1/4

1/7