Question

The inside of a house is at 20°C on an early morning when the temperature outside is 15°C. The next morning the inside temperature is the same but the outside temperature is now 10°C. How much does the energy per unit time lost by conduction through the walls, windows, doors, etc., change for the house from the first morning to the second one?

a) Since the inside temperature stays the same, the loss is the same both days.

b) The loss doubles.

c) The loss halves.

d) The loss increases

Answer #1

**in conduction process the amount of heat transfer is
directly**

**proportional to the temperature difference ,area of
cross
section and inversely propotional to the thickness**

**H = dQ/dt = K*A*dT/x**

**K = coefficient of conductivity**

**here**

**on the first day the temperature difference dT1 = 20-15 =
5**

**on the next day the temperature difference = dT2 = 20-10 =
10**

**the ramining parameters ar same**

**so**

**H2/H1 = dT2/dT1**

**H2/ H1 = 10/5 = 2**

**H2 = 2H1**

**the loss doubles**

**option b)**

An ideal heat pump is used to maintain the inside of a house at
22◦C when the outside temperature is Tout. Assume the pump does
work at the rate of 1500W. The house loses heat by conduction
(through walls, windows, etc.) at a rate given by (Tin − Tout) ×
650W/ ◦C
(a) For what outside temperature would the pump have to operate
all the time in order to maintain the house at 22◦C?
(b) If the outside temperature is...

Calculate the rate of heat conduction (in W) through house walls
that are 14.5 cm thick and that have an average thermal
conductivity twice that of glass wool. Assume there are no windows
or doors. The surface area of the walls is 145 m2 and
their inside surface is at 21.5°C, while their outside surface is
at 5.00°C.
How many 1 kW room heaters would be needed to balance the heat
transfer due to conduction? (Round your answer to the...

(a)
Calculate the rate of heat conduction (in W) through house walls
that are 15.0 cm thick and that have an average thermal
conductivity twice that of glass wool. Assume there are no windows
or doors. The surface area of the walls is 115 m2 and
their inside surface is at 19.0°C, while their outside surface is
at 5.00°C.
W
(b)
How many 1 kW room heaters would be needed to balance the heat
transfer due to conduction? (Round your...

In the first lesson we talk about the heat transfer that takes
place in the human body, but the same types of transfer occur for
any object. For the following question, use the dimensions and
characteristics of your own home. It’s reasonable to assume that
walls are thick enough to block direct heat loss to radiation
(without prior conduction through the walls). Windows are
relatively thin in comparison and conduct more heat than walls
(i.e. a double-pane glazed window has...

a A heat pump is used to maintain the inside temperature of a
house at 20◦C when the outside temper-ature is 30◦C. What is the
minimum amount of work necessary to transfer 100 J of heat to the
inside of the house? b The heat of combustion of gasoline is
approximately 47.0 kJ/mol. If a gasoline engine operates between
1500 K and 750 K, what is the maximum height that 5.0 moles of
gasoline can lift a 400 kg aircraft?

a. Discuss why car inside temperature is high when you park the
car outside in a sunny day even under the shade and the relation
with glass transmissivity (Greenhouse effect). [5 marks]
b. A double walled spherical tank is used to store iced water at
O'C. The tank internal diameter is 2 m and wall thickness is 0.5
cm. The inner and outer walls are separated with the 2 cm thick
space. The air between the two walls of the...

A house has well-insulated walls 15.0 cm thick (assume
conductivity of air) and area 500 m2 , a roof of wood 5.0 cm thick
and area 270 m2 , and uncovered windows 0.55 cm thick and total
area 30 m2 .
I don't need help with question A, I got it right but i don't
know how to do b and c
A) Assuming that heat is lost only by conduction, calculate the
rate at which heat must be supplied...

8 through 10 done please!!
3.13.6
Question 110 pts
A 319 kg motorcycle is parked in a parking garage. If the car has
35,494 J of potential energy, how many meters above ground is the
car? Report your answer to 1 decimal place. Please do not include
units or the answer will be marked incorrect.
Flag this Question
Question 210 pts
A box sitting on the top of a hill has 252 J of potential energy.
If the hill is...

just do questions 5 through 10
3.13.6
Question 110 pts
A 319 kg motorcycle is parked in a parking garage. If the car has
35,494 J of potential energy, how many meters above ground is the
car? Report your answer to 1 decimal place. Please do not include
units or the answer will be marked incorrect.
Flag this Question
Question 210 pts
A box sitting on the top of a hill has 252 J of potential energy.
If the hill...

Exploring Innovation in Action Power to the People – Lifeline
Energy Trevor Baylis was quite a swimmer in his youth, representing
Britain at the age of 15. So it wasn’t entirely surprising that he
ended up working for a swimming pool firm in Surrey before setting
up his own company. He continued his swimming passion – working as
a part-time TV stuntman doing underwater feats – but also followed
an interest in inventing things. One of the projects he began...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 1 minute ago

asked 3 minutes ago

asked 3 minutes ago

asked 9 minutes ago

asked 27 minutes ago

asked 37 minutes ago

asked 43 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago