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3 years ago

13

Evaporation only occurs at the surface of a liquid

1 answer:

Veseljchak [2.6K]3 years ago

8 0

yes

evaporation starts on the surface

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When the potential energy is high, the kinetic energy is _____.

kramer

Answer:

low then it gets high

Explanation:

none

4 0

3 years ago

In 1976, the SR-71A, flying at 20 km altitude (T = –56 0C), set the official jet-powered aircraft speed record of 3530 km/hr (21

Lapatulllka [165]

To solve this problem we will apply the concepts related to the calculation of the speed of sound, the calculation of the Mach number and finally the calculation of the temperature at the front stagnation point. We will calculate the speed in international units as well as the temperature. With these values we will calculate the speed of the sound and the number of Mach. Finally we will calculate the temperature at the front stagnation point.

The altitude is,

$z = 20km$

And the velocity can be written as,

$V = 3530km/h (\frac{1000m}{1km})(\frac{1h}{3600s})$

$V = 980.55m/s$

From the properties of standard atmosphere at altitude z = 20km temperature is

$T = 216.66K$

$k = 1.4$

$R = 287 J/kg$

Velocity of sound at this altitude is

$a = \sqrt{kRT}$

$a = \sqrt{(1.4)(287)(216.66)}$

$a = 295.049m/s$

Then the Mach number

$Ma = \frac{V}{a}$

$Ma = \frac{980.55}{296.049}$

$Ma = 3.312$

So front stagnation temperature

$T_0 = T(1+\frac{k-1}{2}Ma^2)$

$T_0 = (216.66)(1+\frac{1.4-1}{2}*3.312^2)$

$T_0 = 689.87K$

Therefore the temperature at its front stagnation point is 689.87K

6 0

3 years ago

An ideal gas in a piston is placed in a refrigerator, which removes 413 J of energy from the gas via cooling. The plunger on the

maria [59]

Answer:

The net change in the internal energy of the gas in the piston is -343J

Explanation:

Because heat and workdone are the only means of energy transfer between the system and the surrounding, change in internal energy is given by;

∆E = q + w

q = heat transfer

w = workdone

Because heat is lost by the system, the heat transfer is negative

q = -413J

Because work is done on the system, workdone is positive

w = +70J

∆E = -413J + 70J

∆E = -343J

5 0

3 years ago

Does the moon make its own light?

Stels [109]

Answer:

no it gets it form the sun

Explanation:

8 0

3 years ago

Read 2 more answers

A horse ran 600 m in a time of 33 s. What was the average speed of the<br> horse?

GalinKa [24]

<h3>Average Speed ≈ 18m/s</h3>

Explanation:

Distance : 600 m

Time : 33 seconds

Average Speed : ?

$Av. Speed = \frac{Distance }{Time} \\ = \frac{600}{33}$

Simplify

$Av. Speed = 18.18181 \\ = 18 \: m {s}^{ - 1}$

5 0

2 years ago