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]
3 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]3 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
1
emmainna [20.7K]

Answer:

Increasing the mass and decreasing the distance between the two objects.

Explanation:

An increase in mass will cause them to have a stronger pull or gravity. A decrease of distance will make it easier for the objects to fall into each other because they would be further into the other objects area of influence.

3 0
3 years ago
Hello, PLEASE ANSWER ASAP!!! Don't report my question or give me false answers but I'm freaking out. I was biking home from scho
kodGreya [7K]

Answer:

just calmly talk and get money to pay them the bike and explain it to them

Explanation:

4 0
3 years ago
Which of these events indicate that a chemical reaction might have occurred?
blagie [28]
Reactions occur when two or more molecules interact and the molecules change. Bonds between atoms are broken and created to form new molecules. That's it.
7 0
3 years ago
With manual transmission, use your right foot for the brake and accelerator and left foot for the clutch true or false
GaryK [48]

This is true!

Hope this helps!

4 0
3 years ago
Read 2 more answers
What do electrons move from
Alona [7]

Answer:

Negatively charged, to positively charged parts

Explanation:

Electrons are negative, negative is attracted to positive.

7 0
3 years ago
Other questions:
  • Consider a constant density gas flowing steadily over an airfoil. Far upstream the velocity is V0. Halfway along the top surface
    13·1 answer
  • A model of an atom is shown above. The blue dots represent electrons, and the red dot represents the nucleus. This model accurat
    9·2 answers
  • A car is traveling at a speed of 50 m/sec when it suddenly accelerates at a rate of 5 m/sec2. How fast will the car be going (fi
    10·1 answer
  • Manuel is holding a 5kg box. How much force is the box exerting on him?In what direction
    13·1 answer
  • A flat square plate of side 20cm moves over other similar plate with a thin layer of 0.4cm of a liquid between them with force 1
    15·1 answer
  • Every time there is a full moon, Mrs. Cook insists that students in her classes display strange behavior. What would be the best
    12·2 answers
  • Which statement describes a climate condition?
    13·1 answer
  • A ball thrown vertically upward is caught by the thrower after 2.93 s. Find the initial velocity of the ball. The acceleration o
    9·1 answer
  • A sound wave has a speed of
    6·1 answer
  • How much power is required to carry a 35 N package a vertical distance of 18 m if the work on the package is accomplished in 30
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!