Hot air enters a rectangular duct (20cm wide, 25cm high, and 5m long) at 100 kPa and 60 degrees C at an average velocity of 5 m/s. While air flows the duct, it gets cool down (loses energy) so that air leave the duct at 54 degrees C. Determine the rate of heat loss from the air under steady condition
Answers
Answer:
1.57 kW
Explanation:
The rate of heat loss is given by:
q = Gm * Cp * (tfin - ti)
Where
q: rate of heat loss
Gm: mass flow
Cp: specific heat at constant pressure
The Cp of air is:
Cp = 1 kJ/(kg*K)
The mass flow is the volumetric flow divided by the specific volume
Gm = Gv / v
The volumetric flow is the air speed multiplied by the cruss section of the duct.
Gv = s * h * w (I name speed s because I have already used v)
The specific volume is obtained from the gas state equation:
p * v = R * T
60 C is 333 K
The gas constant for air is 287 J/(kg*K)
Then:
v = (R * T)/p
v = (287 * 333) / 100000 = 0.955 m^3/kg
Then, the mass flow is
Gm = s * h * w / v
And rthe heat loss is of:
q = s * h * w * Cp * (tfin - ti) / v
q = 5 * 0.25 * 0.2 * 1 * (54 - 60) / 0.955 = -1.57 kW (negative because it is a loss)
Related Questions
Use the worked example above to help you solve this problem. A ball is thrown upward from the top of a building at an angle of 30.0° to the horizontal and with an initial speed of 15.0 m/s. The point of release is h = 46.0 m above the ground.(a) How long does it take for the ball to hit the ground?(b) Find the ball's speed at impact.(c) Find the horizontal range of the ball.
Describe the objects that make up Saturn's rings. Your answer should include the range of sizes of objects in the rings, and the composition of the at least the outer layers of the objects.
A stunt driver rounds a banked, circular curve. The driver rounds the curve at a high, constant speed, such that the car is just on the verge of skidding to the outside of the curve. A front view of a car driving on a banked curve. The cross section of the banked road is constructed like a ramp. The car drives transversely to the slope of the ramp, so that the wheels of one side of the car are lower than the wheels on the other side of the car. Which forces are directly responsible for producing the car’s centripetal acceleration? Coriolis force centripetal force frictional force normal force gravitational force
a. of water a. of bread a. of soap a. of juice a. of packet a. of sand option_piece packet grain bottle cake slice bale tank pane note tube bar can sack pile sheaf
Answers
Answer:
Improvement in observational, and exploratory technology
Rapid increase in knowledge
International collaboration
Explanation:
Our knowledge of the solar system has increased greatly in the past few years due to to some factors which are listed below.
Improvement in observational, and exploratory technology: In recent years, developments in technology has led to the invention of advanced observational instruments and probes, that are used to study the solar system. Also more exploratory units are now developed to go out into the solar system and gather useful data which is then further processed to yield more results about our solar system.
Rapid increase in knowledge: The past few years has seen an increased number of theories proposed to explain phenomena in the solar system. Some of these theories have been seen to be accurate under experimentation, leading to newer and fresher insights into our solar system. Also, new experiments and research are carried out, all these leading to an exponential growth in our knowledge of the solar system.
International Collaboration: The sharing of knowledge by scientists all over has led to a better, quick understanding of the solar system. Also, scientists from different countries, working together on different experiment and data sharing regarding our solar system now allows our knowledge of the solar system to deepen faster.
Answers
where I is the moment of inertia. This is just mass times the square of the perpendicular distance to the axis of rotation. In other words, the radius of the propeller or this is equivalent to the length of the rod. ω is the angular velocity. We determine I and ω first.
ω = 573 rev/min * (2π rad/rev) * (1 min/60 s) = 60 rad/s
Then,
Answer:
4833J
Explanation:
Length=0.777
mass=2.67
# rods= 5
ω=573 rpm--> rad/s
I=kgm^2
K=1/2(number of rods)(I)(ω)=J
I know it's very late, but hope this helps anyone else trying to find the answer.
4.0
5.0
2.4
1.6
Answer and I will give you brainiliest
Answers
Answer:
2.4
Explanation:
Hope it help mark as Brainlist
Answers
Answer:
Temperature = 20.35°C
Explanation:
Arrhenius equation is as follows:
k = A*exp(-Ea/(R*T)), where
k = rate of chirps
Ea = Activation Energy
R = Universal Gas Constant
T = Temperature (in Kelvin)
A = Constant
Given Data
Ea = 53.9*10^3 J/mol
R = 8.3145 J/(mol.K)
T = 273.15 + 25 K
k = 178 chirps per minutes
Calculation
Using the Arrhenius equation, we can find A,
A= 4.935x10^11
Now we can apply the same equation with the data below to find T at k=126,
k = A*exp(-Ea/(R*T))
Ea = 53.9*10^3
R = 8.3145
k = 126
T = 20.35°C
Answers
Answer:
The number is
Explanation:
From the question we are told that
The net charge is
Generally the charge on a electron is
Generally the number of excess electrons is mathematically represented as
=>
=>
b) 6.67x10-19hz
c) 3x108hz
d) 1.5hz
Show calculation
Answers
Answer:
1.5 x 10¹⁸hz
Explanation:
Given parameters:
Wavelength = 2 x 10⁻¹⁰m
Unknown:
Frequency = ?
Solution:
To find the frequency, use the expression below;
V = f x wavelength
V is the speed of light = 3 x 10⁸m/s
f is the frequency
Now;
Insert the parameters
3 x 10⁸ = 2 x 10⁻¹⁰ x frequency
Wavelength = = 1.5 x 10¹⁸hz