physics

posted by .

Suppose that you want to freeze 1.2 kg of water for a party, and only have 10 minutes to do it. Relying on nothing but your keen physical abilities, a dixie cup, duct tape and a piece of string, you manage to build a refrigerator unit which can do the job.
The temperature inside the refrigeration unit is 273 K, and the temperature outside is Thot = 301 K. Since you are a brilliant UW student, assume that your refrigerator has the maximum possible efficiency. Assume also that the initial temperature of the water is 273 K. The Latent Heat of Fusion of water is 3.33×105 J/kg.

(a) What is the heat flow ( Qcold / time ) out of the cold well per second in J/s?
Hcold = Qcold / time = J/s *
666 OK

(b) What is the change in entropy in the water per second in J/K s?
ΔS / time = J/K s

HELP: Change in entropy = Change in energy / Absolute Temperature.

HELP: To get the change in entropy of the water, use the total heat of fusion for the 1.2 kg of water. The water freezes at 273 K, and it all happens over a period of 10×60 seconds.

(c) What is the heat flow ( Qhot / time ) into the hot well per second in J/s?
Hhot = Qhot / time = J/s

(d) How much POWER must you provide to drive your refrigerator, in Watts? (That is, work done per second?)
Power = W

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. physics

    I need to make an egg protection device using only sipping straws and duct tape. Any ideas?
  2. Chemistry

    Physical properties are those that you can detect with your senses: sight, hearing, touch, taste, smell. With just a glass of water, you can explore physical properties of water. Activity: Investigating Water glass of drinking water,paper …
  3. Chemistry

    Physical properties are those that you can detect with your senses: sight, hearing, touch, taste, smell. With just a glass of water, you can explore physical properties of water. Activity: Investigating Water glass of drinking water,paper …
  4. Physics

    Refrigerator Suppose that you want to freeze 1.2 kg of water for a party, and only have 10 minutes to do it. Relying on nothing but your keen physical abilities, a dixie cup, duct tape and a piece of string, you manage to build a refrigerator …
  5. physics

    A cylindrical air duct in an air conditioning system has a length of 3.5 m and a radius of 5.00 m. A fan forces air (ç = 1.8 Pa·s) through the duct, such that the air in a room (volume = 242 m3) is replenished every 12 minutes. Determine …
  6. physics

    A cylindrical air duct in an air conditioning system has a length of 3.5 m and a radius of 5.00 X 10^-2 m. A fan forces air (ç = 1.8 X 10^-5 Pa·s) through the duct, such that the air in a room (volume = 242 m3) is replenished every …
  7. Physics

    Suppose you have a very long straw that can reach from a cup of water on the ground level to the top of a very tall building. When you use a pump to suck on the straw in order to bring water up, a. you can bring the water up to any …
  8. Physics

    Suppose you have a very long straw that can reach from a cup of water on the ground level to the top of a very tall building. When you use a pump to suck on the straw in order to bring water up, a. you can bring the water up to any …
  9. Riddle

    PLEASE HELP I DONT KNOW THE ANSWER! Riddle: You wake up in a room with only one door and no windows. On the ground is two specially made peices of string, a candle and a piece of paper. The string are at different lengths but both …
  10. HVAC

    Two HVAC/R technicians are discussing the tape used in HVAC/R repairs. Technician A says that cloth duct tape is preferred for use in attics. Technician B says that UL 181 tape is normally required for duct closing systems. Which one …

More Similar Questions