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Leona [35]
3 years ago
6

You prepare tea with 0.250 kg of water at 85.0 ºC and let it cool down to room temperature (20.0 ºC) before drinking it. Essenti

ally, the cooling process is isothermal to the air in your kitchen. Calculate the entropy change of the air as the tea cools, assuming that all the heat lost by the water goes into the air
Physics
1 answer:
vladimir2022 [97]3 years ago
5 0

Answer:

232 J/K

Explanation:

The amount of heat gained by the air = the amount of heat lost by the tea.

q_air = -q_tea

q = -mCΔT

q = -(0.250 kg) (4184 J/kg/ºC) (20.0ºC − 85.0ºC)

q = 68,000 J

The change in entropy is:

dS = dQ/T

Since the room temperature is constant (isothermal):

ΔS = ΔQ/T

Plug in values (remember to use absolute temperature):

ΔS = (68,000 J) / (293 K)

ΔS = 232 J/K

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3 years ago
A car travels 210 miles in t hours at a speed of r mph. if the car travels half as fast but five times as long, how far does it
Kobotan [32]
The car travls 400mph

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If an ideal fluid element moves from a region of lower pressure to a region of higher pressure, is the work done on it by the pr
nikklg [1K]

Answer:

Positive

Explanation:

An ideal fluid is on which is incompressible and non-viscous.

In an ideal fluid element when a fluid element moves from a region of high pressure to region of low pressure then the work done on the fluid element is positive because the force acts in the direction from high pressure towards low pressure and displaces the fluid element, so the work-done is positive.

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3 years ago
Can include a single word part on one side , with the meaning on the other side . Stephen can test himself or can enlist the hel
BARSIC [14]

Incomplete question; Full question read;

Type the correct answer in the box. Spell all words correctly. Stephen is a student who wants to test his knowledge of medical terminology. <u>Which option could he use?</u>

For medical terminology, ___________ can include a single word part on one side, with the meaning on the other side. Stephen can test himself or can enlist the help of someone else to hold them up to test him.

Answer:

<u>Flashcard</u>

Explanation:

It is interesting to note that a flashcard is an effective memory and teaching aid. It usually<em> has a question on one side, and the other side contains the answer.</em>

Hence, Stephen can build his knowledge of medical terminology by making use of a flashcard himself or can enlist the help of someone else to hold them up to test him.

7 0
3 years ago
A ski jumper travels down a slope and leaves
Serhud [2]

Question seems to be missing. Found it on google:

a) How long is the ski jumper airborne?

b) Where does the ski jumper land on the incline?

a) 4.15 s

We start by noticing that:

- The horizontal motion of the skier is a uniform motion, with constant velocity

v_x = 28 m/s

and the distance covered along the horizontal direction in a time t is

d_x = v_x t

- The vertical motion of the skier is a uniformly accelerated motion, with initial velocity u_y = 0 and constant acceleration g=9.8 m/s^2 (where we take the downward direction as positive direction). Therefore, the vertical distance covered in a time t is

d_y = \frac{1}{2}gt^2

The time t at which the skier lands is the time at which the skier reaches the incline, whose slope is

\theta = 36^{\circ} below the horizontal

This happens when:

tan \theta = \frac{d_y}{d_x}

Substituting and solving for t, we find:

tan \theta = \frac{\frac{1}{2}gt^2}{v_x t}= \frac{gt}{2v_x}\\t = \frac{2v_x}{g}tan \theta = \frac{2(28)}{9.8} tan 36^{\circ} =4.15 s

b) 143.6 m

Here we want to find the distance covered along the slope of the incline, so we need to find the horizontal and vertical components of the displacement first:

d_x = v_x t = (28)(4.15)=116.2 m

d_y = \frac{1}{2}gt^2 = \frac{1}{2}(9.8)(4.15)^2=84.4 m

The distance covered along the slope is just the magnitude of the resultant displacement, so we can use Pythagorean's theorem:

d=\sqrt{d_x^2+d_y^2}=\sqrt{(116.2)^+(84.4)^2}=143.6 m

7 0
3 years ago
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