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
ladessa [460]
2 years ago
7

A closed, rigid tank fitted with a paddle wheel contains 2 kg of air, initially at 300 K. During an interval of 5 minutes, the p

addle wheel transfers energy to the air at a rate of 1 kW. During the interval, the air also receives energy by heat transfer at a rate of .5 kW. These are the only energy transfers. Assuming the ideal gas model for the air, and no overall changes in kinetic or potential energy, determine the final temperature of the air, in K.

Physics
1 answer:
anzhelika [568]2 years ago
3 0

Answer:

The final temperature of the air is T_2= 605 K

Explanation:

We can start by doing an energy balance for the closed system

\Delta KE+\Delta PE+ \Delta U = Q - W

where

\Delta KE = the change in kinetic energy.

\Delta PE = the change in potential energy.

\Delta U = the total internal energy change in a system.

Q = the heat transferred to the system.

W = the work done by the system.

We know that there are no changes in kinetic or potential energy, so \Delta KE = 0 and \Delta PE=0

and our energy balance equation is \Delta U = Q - W

We also know that the paddle-wheel transfers energy to the air at a rate of 1 kW and the system receives energy by heat transfer at a rate of 0.5 kW, for 5 minutes.

We use this information to calculate the total internal energy change \Delta U=W+Q using the energy balance equation.

We convert the interval of time to seconds t = 5 \:min = 300\:s

\Delta \dot{U}=\dot{W}+ \dot{Q}\\=\Delta U=(W+ Q)\cdot t

\Delta U=(1 \:kW+0.5\:kW)\cdot 300\:s\\\Delta U=450 \:kJ

We can use the change in specific internal energy \Delta U = m(u_2-u_1) to find the final temperature of the air.

We are given that T_1=300 \:K and the air can be describe by ideal gas model, so we can use the ideal gas tables for air to determine the initial specific internal energy u_1

u_1=214.07\:\frac{kJ}{kg}

Next, we will calculate the final specific internal energy u_2

\Delta U = m(u_2-u_1)\\\frac{\Delta U}{m} =u_2-u_1

\frac{\Delta U}{m} =u_2-u_1\\u_2=u_1+\frac{\Delta U}{m}

u_2=214.07 \:\frac{kJ}{kg} +\frac{450 \:kJ}{2 \:kg}\\u_2= 439.07 \:\frac{kJ}{kg}

With the value u_2=439.07 \:\frac{kJ}{kg} and the ideal gas tables for air we make a regression between the values u = 434.78 \:\frac{kJ}{kg},T=600 \:K and u = 442.42 \:\frac{kJ}{kg}, T=610 \:K and we find that the final temperature T_2 is 605 K.

You might be interested in
The graph represents velocity over time. What is the acceleration? –0.4 m/s2 –0.2 m/s2 0.2 m/s2 0.4 m/s2
Olenka [21]
Missing graph. I attach it in the answer.

In a uniformly accelerated motion, the velocity at time t is given by:
v(t)=at
where a is the acceleration and t is the time.

Given the previous equation, if we plot v(t) versus t, we find a straight line; moreover, a (the acceleration) represents the slope of the curve.

Looking at the graph, we see that when the time goes from 10 s to 20 s, the velocity increases from 4 m/s to 6 m/s. Therefore the slope of the curve is
a= \frac{\Delta v}{\Delta t}= \frac{6 m/s-4 m/s}{20 s-10 s}= \frac{2 m/s}{10 s}=0.2 m/s^2
and this corresponds to the acceleration.

So, the correct answer is <span>0.2 m/s2.</span>

7 0
3 years ago
Read 2 more answers
What is the direction of the force of an object moving in a circle?
Ivanshal [37]

Answer:

The answer is 45 degree angle

7 0
3 years ago
Olivia is on a swing at the playground at which point is her kinetic energy increasing and her potential energy decreasing
Nimfa-mama [501]
Whenever an object is falling, its potential energy
is decreasing and its kinetic energy is increasing.

Olivia's potential energy is decreasing and her kinetic energy
is increasing as she moves toward the right side of the picture,
all the way from W, through X, to the bottom of the arc.
7 0
3 years ago
Read 2 more answers
Voices of swimmers at a pool travel 400 m/s through the air and 1,600 m/s underwater. The wavelength changes from 2 m in the air
frosja888 [35]

The frequency of the wave has not changed.

In fact, the frequency of a wave is given by:

f=\frac{v}{\lambda}

where v is the wave's speed and \lambda is the wavelength.

Applying the formula:

- In air, the frequency of the wave is:

f=\frac{400 m/s}{2 m}=200 Hz

- underwater, the frequency of the wave is:

f=\frac{1600 m/s}{8 m}=200 Hz

So, the frequency has not changed.

3 0
3 years ago
Read 2 more answers
For each of the statements below, decide which of the Maxwell equations (forstaticsituations) tells you that the statement is tr
Vladimir79 [104]

Answer:

(a)There are no magnetic monopoles. true

(c) There must be a vector potential. true

(d) Charges create electric fields.2. true

Explanation:

a) there are no magnetic monopoles because magnetic field is created by charges (electrons) and these electrons have dipole field so it is not possible to have magnetic dipoles, more ever Gauss's law always explained that there are not magnetic dipoles. furthermore magnetic monopoles aree caused by magnetic charges and we have electric charges.

c)vector potential is a vector field which serves as a potential for magnetic field so, the magnetic field B by Faraday and Gauss's law is also known as vector potential.

d) electric field is solely generated by charges be it static charges or moving charges if there are no charges it is not possible to have an electric field.

3 0
3 years ago
Other questions:
  • Using a rope that will snap if the tension in it exceeds 379 N, you need to lower a bundle of old roofing material weighing 473
    8·1 answer
  • (b) An example of an inverse square field is the gravitational field F = −(mMG)r/|r|3. Use part (a) to find the work done by the
    6·1 answer
  • Small-plane pilots regularly compete in "message drop" competitions, dropping heavy weights (for which air resistance can be ign
    5·1 answer
  • An optical disk drive in your computer can spin a disk up to 10,000 rpm (about 1045 rad/s). If a particular disk is spun at 646.
    6·1 answer
  • Someone help me pls
    15·1 answer
  • Oceanic crust that records negative magnetic anomalies formed when the earth's magnetic field was ___________.
    15·1 answer
  • You lay a rectangular board on the horizontal floor and then tilt the board about one edge until it slopes at angle 0 with the h
    5·1 answer
  • A scientist is using an objective lens with 40X magnification on his microscope. If the ocular lens magnifies 10X, what is the t
    7·1 answer
  • What do car manufacturers do to reduce the fluid friction acting on a car
    9·2 answers
  • I need this to be correct and explane why its that answer.
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!