Question

A loaf of bread is removed from an oven at 350◦F and cooled in a room whosetemperature is 70◦F. If the bread cools to 210◦F in 20 minutes, how much longer willit take the bread to cool to 150◦F.

Answer #1

1. A potato is removed from an oven with the temperature 350
degrees F. It is placed on a plate in a room with temperature 75
degrees F. After 5 minutes, the potato has a temperature of 240
degrees F. When will the potato be 85 degrees F?

A freshly baked loaf of bread (30cm long, 15cm high, 10 cm wide)
is removed from an oven and set on the counter (assumed insulated)
to cool. The bread is at 125°C initially (assume uniform) and the
room is at 25°C. Thermal conductivity and diffusivity for bread are
k=0.05 W/m•K and α=5x10-7 m2/s, and the convective heat
transfer coefficient is h=10 W/m2K.
(a) Write down the governing differential equation in
three-dimension representing this problem.
(b) Write down the boundary conditions...

A plate is removed from an oven at temperature of 50◦C and
placed in a large room at 20◦C . After 5 minutes the temperature of
the plate is 40◦C . How much longer will it take to reach 30◦ ?
So far I think I have only learnt about Newton's Law of Cooling,
so if the answer could be relative to that formula that would be
helpful in my understanding.

Suppose that a cup of soup cooled from 90C to 50C after 25
minutes in a room whose temperature was 20C. Use Newton's law of
cooling to answer the following questions.
a. How much longer would it take the soup to cool to 30C? (in
minutes)
b. Instead of being left to stand in the room, the cup of 90C
soup is put in the freezer whose temperature is -15C. How long will
it take the soup to cool from...

A thermometer is removed from a room where the temperature is
70° F and is taken outside, where the air temperature is 20° F.
After one-half minute the thermometer reads 60° F. What is the
reading of the thermometer at t = 1 min? (Round your answer to two
decimal places.)
How long will it take for the thermometer to reach 35° F? (Round
your answer to two decimal places.) min

A thermometer is removed from a room where the temperature is
70° F and is taken outside, where the air temperature is 30° F.
After one-half minute the thermometer reads 60° F. What is the
reading of the thermometer at
t = 1 min?
(Round your answer to two decimal places.) ° F
How long will it take for the thermometer to reach 35° F? (Round
your answer to two decimal places.)

Read the instructions below and answer the questions
Preheat the oven to 350°F. Spray a cookie sheet with a
non-stick spray. Roll the previously refrigerated cookie dough into
1-inch balls. Arrange on the cookie sheet 2cm apart. When the oven
is hot, bake for 12 to 15 minutes or until golden brown. Transfer
to cookie rack 5 minutes before eating.
39. Which of the following step should the baker take
immediately before rolling the cookie dough into balls?
a. Preheat...

The oven was at room temperature 70℉. Just after it was turned
on, the temperature rose 40℉ per minute. What does the independent
variable represent? What does the dependent variable represent?
Graph your results. Be sure to graph the independent variable on
the horizontal axis. What will the temperature of the oven be after
6 minutes? Write an algebraic model (equation) for this
application. How long will it take before the temperature is
450℉.

6. Ice at 0 0C is used to cool water from room temperature (20
0C) to 0 0C. How much water can be cooled by 1 kg of ice?

A cup of coffee has a temperature of 200F. It is placed in a
room that has temperature 70 F. After 15 minutes, the temperature
of the coffee is 150F.
a) Model the temperature of the cup of coffee at time t.
b) How long will it take for the coffee to cool down to 100◦
F?

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