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kiruha [24]
3 years ago
11

The air contained in a room loses heat to the surroundings at a rate of 50 kJ/min while work is supplied to the room by computer

, TV, and lights at a rate of 1.2 kW. What is the net amount of energy change of the air in the room during a 30-min period?

Engineering
2 answers:
Mkey [24]3 years ago
8 0

Answer:

660KJ

Explanation:

Given

Let Q = Heat Loss from room = 50kj/min

Let W = Work Supplied to room = 1.2KW

1 kilowatt = 1 kilojoules per second

So, W = 1.2KJ/s

In heat and work (Sign Convention)

We know that

1. Heat takes positive sign when it is added to the system

2. Heat takes negative sign when it is removed from the system.

3. Work done is considered positive when work is done by the system

4. Work done is considered negative when work is done on the system.

From the above illustration, heat loss (Q) = -50KJ/Min

In 30 minutes time, Q = -50Kj/Min * 30 Min

Work done in 30 minutes = -1500 KJ

Also, work supplied = -1.2Kj/s

Work supplied to the system in 30 minutes = -1.2Kj/s * 30 minutes

W = -1.2 KJ/s * 30 * 60 seconds

W = -2160KJ

In thermodynamics (First Law)

Q = W + ΔU

-1500 = -2160 + ΔU

∆U = 2160 - 1500

∆U = 660KJ

Artemon [7]3 years ago
4 0

Answer:

net amount of energy change of the air in the room during a 30-min period = 660KJ

Explanation:

The detailed calculation is as shown in the attached file.

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Explain about Absolute viscosity, kinematic viscosity and SUS?
ArbitrLikvidat [17]

Answer:

Absolute viscosity is the evaluation of the resistance (INTERNAL) of the fluid  flow

Kinematic viscosity relates to the dynamic viscosity and density proportion.

SUS stands for Sabolt Universal Seconds. it is units which described the variation of oil viscosity

Explanation:

Absolute viscosity is the evaluation of the resistance (INTERNAL) of the fluid  flow, whereas Kinematic viscosity relates to the dynamic viscosity and density proportion. fluid with distinct kinematic viscosities may have similar dynamic viscosities and vice versa.Dynamic viscosity provides you details of  power required to make the fluid flow at some rate, however kinematic viscosity shows how quick the fluid moves when applying a certain force.

SUS stands for Sabolt Universal Seconds. it is units which described the variation of oil viscosity when change with change in temperature. it is measured by using viscosimeter.

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3 years ago
g The parameters of a certain transmission line operating at 휔휔=6 ×108 [rad/s] are 퐿퐿=0.35 [휇휇H/m], 퐶퐶=75 [pF/m], 퐺퐺=75 [휇휇S/m],
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Explanation:

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-\alpha-0.094 \mathrm{Np} / \mathrm{m} . \quad 3-2.25 \mathrm{rad} / \mathrm{m}, \text { and } \lambda-2 \pi / \beta-\underline{2.79} \mathrm{m}

Z_{0}-\sqrt{\frac{Z}{Y}}-\sqrt{\frac{R+j \omega L}{G+j \omega C}}-\sqrt{\frac{17+j 2.1 \times 10^{2}}{75 \times 10^{-6}+j 2.4 \times 10^{-2}}}-\frac{93.6-j 3.64 \Omega}{4}

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stira [4]

Answer:

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Explanation:

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Total Distance Traveled = S = 100 mi + 100 mi

S = 200 mi

Now, for total time, we calculate the times for both speeds from A to b and then B to C, separately and add them.

Total Time = t = Time from A to B + Time from B to C

t = (100 mi)/(50 mi/h) + (100 mi)(70 mi/h)

t = 2 h + 1.43 h

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Now, the average speed of bus will be given as:

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It is clear from this answer that the correct option is:

<u>c. less than 60 mi/h</u>

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