1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Stella [2.4K]
2 years ago
10

Under conditions for which the same roojm temperature is mainteined bt a heating or cooling system, it is not uncommon for a per

son to feel chilled in the winter but comfortable in the summer. Provide a plausible explanation for this situation (with supporting calculations) y by considering a room whose air temperature is maintained at 20 Dagree C throughout the year, while the walls of the room are nominally at 27 Dagree C and 14 Dagree C in the summer and winter, respectively. The exposed surface of a person in the room may be assumed to be at a temperature of 32 Dagree C throughout the year and to have an emissivity of 0.90. The coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 W/m2 Middot K.
Engineering
1 answer:
bonufazy [111]2 years ago
7 0

Answer:

Net heat transfers:  during summer = 52.253 W/m^2 during winter = 119.375 w/m^2

Explanation:

Given data :

Room temperature throughout the year = 20⁰c = 293 k

Room temperature during summer = 27⁰c = 300 k

Room temperature during winter = 14⁰c = 287 k

surface temperature of a person throughout the year = 32⁰c = 305 k

coefficient of heat transfer by natural convection (h)= 2 w /m^2 k

emissivity = 0.9

An explanation to the condition of feeling chilled during the winter and comfortable during summer  can be explained with the calculation below

The heat transfer from the surface body of a person the the room is carried out by convection and this can be calculated as

q = hΔt = 2 * ( 305  -  293) = 2 * 12 = 24 w /m^2

also calculate heat transfer through radiation using this formula

q_{rad} = εσ [ (Temperature of body)^4- (temperature of room at each season)^4 ]

ε = 0.90,(emissivity)    σ = 5.67 *10^-8 w/^2 . k ( Boltzmann's constant)

during summer :

q_{rad} = (0.90)*(5.67*10^-8)* ( 305^4 - 300^4 ) = 28.253 W/m^2

therefore the net heat transfer during the summer = 24 w/m^3 + 28.253 W/m^3 = 52.253 W/m^2

During winter :

q_{rad} = (0.90)*(5.67*10^-8) * ( 305^4 - 287^4 ) = 95.375 W/m^3

therefore the net heat transfer during the winter

= 24 w/m^3 + 95.375w/m^3 = 119.375 w/m^2

You might be interested in
Without motorcycle riders are at risk of severe injury in a crash ?
nekit [7.7K]

Answer:

The correct option is;

A. proper protection

Explanation:

Motorcycle riders ride the motorcycle while at some level of speed while  having the entire body exposed to be a major part of any collision.

Injuries sustained from motorcycle accidents are several times more severe than injuries sustained by occupants of a car that is fully protected by the metallic panel in the same and even more serious accident scenarios

Hence, motorcycle riders require adequate protection by putting on available motorcyclist safety gear

Therefore, to reduce the risk of severe injury n a crash, motorcycle riders require proper protection.

5 0
3 years ago
Read 2 more answers
For which of the following structures would a pile foundation be appropriate? (Select all that apply.)
tiny-mole [99]

Answer:

Football stadium on rocky soil

Skyscraper on bedrock

Apartment building on sandy soil

Explanation:

6 0
3 years ago
3. (a) (5 points) Suppose N packets arrive simultaneously to a link at which no packets are currently being transmitted or queue
Bezzdna [24]

Answer:

(N-1) × (L/2R) = (N-1)/2

Explanation:

let L is length of packet

R is rate

N is number of packets

then

first packet arrived with 0 delay

Second packet arrived at = L/R

Third packet arrived at = 2L/R

Nth packet arrived at = (n-1)L/R

Total queuing delay = L/R + 2L/R + ... + (n - 1)L/R = L(n - 1)/2R

Now

L / R = (1000) / (10^6 ) s = 1 ms

L/2R = 0.5 ms

average queuing delay for N packets = (N-1) * (L/2R) = (N-1)/2

the average queuing delay of a packet = 0 ( put N=1)

4 0
3 years ago
A disk is rotating around an axis located at its center. The angular velocity is 0.5 rad/s. The radius of the disk is 0.4 m. Wha
dimaraw [331]

Answer:

0.2 m/s

Explanation:

The velocity of a point on the edge of a disk rotating disk can be calculated as:

v=\omega*r

Where \omega is the angular velocity and r the radius of the disk. This leads to:

v=0.5\,rad/s\,*\,0.4\,m=0.2\,m/s

4 0
3 years ago
Read 2 more answers
Technician A says vehicles with electronic throttle control do not need a separate cruise control module, stepper motor, or cabl
8_murik_8 [283]

Answer: its A

Explanation:

3 0
3 years ago
Other questions:
  • To water his lawn, a homeowner uses two hoses. One connects to the faucet, the other to the end of the first hose to make the ho
    14·1 answer
  • Identify an object in your house that contains a physical system and list three questions you could use to define the system
    15·1 answer
  • Water is the working fluid in an ideal Rankine cycle. Superheatedvapor enters the turbine at 10MPa, 480°C, and the condenser pre
    10·1 answer
  • For a fluid flowing through a pipe assuming that pressure drop per unit length of pipe (P/L) depends on the diameter of the pipe
    15·1 answer
  • Getting a haircut from a barber is an example of a service that can be purchased. Please select the best answer from the choices
    9·2 answers
  • Question 9 of 25
    12·1 answer
  • Guys, can you rate this toolbox, please. It is my DT project, made for car trips, what do you think of the idea/design/usability
    12·1 answer
  • 53. The plan of a building is in the form of a rectangle with
    13·1 answer
  • Which of the following is a purpose of sports biomechanics?
    14·1 answer
  • Which of following is not malicious ?<br> Worm<br> Trogan Horse<br> Driver<br> Virus
    8·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!