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
Serjik [45]
3 years ago
9

A closed system of mass 10 kg undergoes a process during which there is energy transfer by work from the system of 0.147 kJ per

kg, an elevation decrease of 50 m, and an increase in velocity from 15 m/s to 30 m/s. The specific internal energy decreases by 5 kJ/kg and the acceleration of gravity is constant at 9.7 m/s^2. Determine the heat transfer for the process, in kJ.
Engineering
2 answers:
mr_godi [17]3 years ago
7 0

Answer:

-50.005 KJ

Explanation:

Mass flow rate = 0.147 KJ per kg

mass= 10 kg

Δh= 50 m

Δv= 15 m/s

W= 10×0.147= 1.47 KJ

Δu= -5 kJ/kg

ΔKE + ΔPE+ ΔU= Q-W

0.5×m×(30^2- 15^2)+ mgΔh+mΔu= Q-W

Q= W+ 0.5×m×(30^2- 15^2) +mgΔh+mΔu

= 1.47 +0.5×1/100×(30^2- 15^2)-9.7×50/1000-50

= 1.47 +3.375-4.8450-50

Q=-50.005 KJ

lilavasa [31]3 years ago
5 0

Answer:

50.005 kJ of heat is transferred by the system

Solution:

As per the question:

Mass of the closed system, m = 10 kg

Decrease in elevation, d = 50 m

Initial velocity, v = 15 m/s

Final velocity, v' = 30 m/s

Change in internal energy, dU = - 5 kJ/kg = - 5000(10 kg) = - 50000 J

As per the first thermodynamics' law:

dQ = dW + (dPE +dKE + dU)            (1)

where

dQ = heat transfer change

dPE +dKE + dU = dE = change in the energy of the system

PE = Potential Energy

KE = Kinetic Energy

U = Internal energy

Now,

dPE = mgd = - 10\times 9.7\times 50 = 4850 J = - 4.850 kJ

(Since, the elevation decreases and hence PE decreases)

dKE = \frac{1}{2}m(v'^{2} - v^{2}) = \frac{1}{2}\times 10(30^{2} - 15^{2}) = 3375 J = 3.375 kJ

Work done, dW = 0.147\times 10^{3}\times 10 = 1470 J

Therefore, using the respective energy values in eqn (1):

dQ = 1470 + (- 4850 + 3375 - 50000) = - 50005 J = - 50.005 kJ

You might be interested in
Does anyone know what this is​
sammy [17]

Answer:

Looks like mold that got frosted over

Explanation:

4 0
2 years ago
Read 2 more answers
Consider the expansion of a gas at a constant temperature in a water-cooled piston-cylinder system. The constant temperature is
Leona [35]

Answer:

Q_{in} = W_{out} = nRT ln (\frac{V_{2}}{V_{1}})

Explanation:

According to the first thermodynamic law, the energy must be conserved so:

dQ = dU - dW

Where Q is the heat transmitted to the system, U is the internal energy and W is the work done by the system.

This equation can be solved by integration between an initial and a final state:

(1) \int\limits^1_2 {} \, dQ = \int\limits^1_2 {} \, dU - \int\limits^1_2 {} \, dW

As per work definition:

dW = F*dr

For pressure the force F equials the pressure multiplied by the area of the piston, and considering dx as the displacement:

dW = PA*dx

Here A*dx equals the differential volume of the piston, and considering that any increment in volume is a work done by the system, the sign is negative, so:

dW = - P*dV

So the third integral in equation (1) is:

\int\limits^1_2 {- P} \, dV

Considering the gas as ideal, the pressure can be calculated as P = \frac{n*R*T}{V}, so:

\int\limits^1_2 {- P} \, dV = \int\limits^1_2 {- \frac{n*R*T}{V}} \, dV

In this particular case as the systems is closed and the temperature constant, n, R and T are constants:

\int\limits^1_2 {- \frac{n*R*T}{V}} \, dV = -nRT \int\limits^1_2 {\frac{1}{V}} \, dV

Replacion this and solving equation (1) between state 1 and 2:

\int\limits^1_2 {} \, dQ = \int\limits^1_2 {} \, dU + nRT \int\limits^1_2 {\frac{1}{V}} \, dV

Q_{2} - Q_{1} = U_{2} - U_{1} + nRT(ln V_{2} - ln V_{1})

Q_{2} - Q_{1} = U_{2} - U_{1} + nRT ln \frac{V_{2}}{V_{1}}

The internal energy depends only on the temperature of the gas, so there is no internal energy change U_{2} - U_{1} = 0, so the heat exchanged to the system equals the work done by the system:

Q_{in} = W_{out} = nRT ln (\frac{V_{2}}{V_{1}})

4 0
3 years ago
If a lever operates at a mechanical disadvantage, it means that the ________.
alekssr [168]

Answer:

The correct answer is option 'B': Load is far from fulcrum and the effort is applied near the fulcrum

Explanation:

A lever works on the principle of balancing of torques. The torque about the fulcrum by the load should be equal to the torque by the applied effort. Since we know that the torque is proportional to both the force and the distance it is applied from the distance from the axis of rotation. A lever is used when we need to lift a heavy load by utilizing this effect of the lever arm.

A mechanical disadvantage occurs when we are not able to lift the weight easily due to the fact we apply effort near the fulcrum.

4 0
3 years ago
Read 2 more answers
What is the IMA of this pulley belt system if the diameter of the input
Stella [2.4K]

Answer:

2.8

Explanation:

The ideal mechanical advantage of the pulley IMA  = D'/D where D' = diameter of output pulley = 7 inches and D = diameter of input pulley = 2.5 inches

So, IMA = D'/D

= 7/2.5

= 2.8

So, the ideal mechanical advantage of the pulley IMA = 2.8

8 0
2 years ago
Calculate the rate at which body heat is conducted through the clothing of a skier in a steady- state process, given the followi
olga2289 [7]

Answer:

230.4W

Explanation:

Heat transfer by conduction consists of the transport of energy in the form of heat through solids, in this case a jacket.

the equation is as follows

Q=\frac{KA(T2-T1)}{L} \\

Where

Q=heat

k=conductivity=0.04

A=Area=1.8m^2

T2=33C

T1=1C

L=thickness=1cm=0.01mQ=\frac{(0.04)(1.8m^2)(33-1)}{0.01m}

Q=230.4W

the skier loses heat at the rate of 230.4W

4 0
3 years ago
Other questions:
  • Air is used as the working fluid in a simple ideal Brayton cycle that has a pressure ratio of 12, a compressor inlet temperature
    13·1 answer
  • 3. Air at 1 atm and 20 0 C flows tangentially on both sides of a smooth flat plate of width W=10 ft and length L=10 ft in the di
    8·1 answer
  • If you add 10 J of heat to a system so that the final temperature of the system is 200K, what is the change in entropy of the sy
    9·1 answer
  • If a motorist moves with a speed of 30 km/hr, and covers the distance from place A to place B
    13·1 answer
  • Might give brainliest
    8·1 answer
  • What are the mechanical properties of a geotextile that are of most importance when using it as a separator in an unpaved road s
    12·1 answer
  • A civil engineer is analyzing the compressive strength of concrete. The compressive strength is approximately normal distributed
    7·1 answer
  • True or False; If I was trying to find the Voltage of my computer, and I was given the Watts and Amps it uses, I would use Watt'
    8·1 answer
  • The cylinder C is being lifted using the cable and pulley system shown.
    8·1 answer
  • What two factors are changing when the current is changed on an electric generator
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!