A small ball is hung by a string from the ceiling of a train car, so that the ball hangs vertically. Moving from

tiny-mole [99]

Yaaaas, do you watch James Charles!?

8 0

4 years ago

Water evaporating from a pond does so as if it were diffusing across an air film 0.15 cm thick. The diffusion coefficient of wat

QveST [7]

Answer:

The water level will drop by about 1.24 cm in 1 day.

Explanation:

Here Mass flux of water vapour is given as

$j_{H_2O}=\frac{D}{l} \bigtriangleup c$

where

$j_{H_2O}$ is the mass flux of the water which is to be calculated.

D is diffusion coefficient which is given as $0.25 cm^2/s$

l is the thickness of the film which is 0.15 cm thick.
$\bigtriangleup c$ is given as

$\bigtriangleup c= \frac{P_{sat}-P_a}{RT}$

In this

$P_{sat}$ is the saturated water pressure, which is look up from the saturated water property at 20°C and 0.5 saturation given as 2.34 Pa

$P_a$ is the air pressure which is given as 0.5 times of $P_{sat}$

R is the universal gas constant as $8.314 kJ/kmol-K$

T is the temperature in Kelvin scale which is $20+273= 293K$

By substituting values in the equation

$\bigtriangleup c= \frac{P_{sat}-P_a}{RT} \\ \bigtriangleup c= \frac{P_{sat}-0.5P_{sat}}{RT} \\ \bigtriangleup c= \frac{0.5P_{sat}}{RT} \\ \bigtriangleup c= \frac{0.5 \times 2.34}{8.314 \times 293} \\\bigtriangleup c= 0.48 mol/m^3$

Converting $\bigtriangleup c$ into $cm^3/cm^3$

As 1 mole of water 18 $cm^3$ so

$\bigtriangleup c= 0.48 mol/m^3 \\ \bigtriangleup c= 0.48 \times 18 \times 10^{-6} cm^3/cm^3 \\ \bigtriangleup c= 8.64 \times 10^{-6} cm^3/cm^3$

Putting this in the equation of mass flux equation gives

$j_{H_2O}=\frac{D}{l} \bigtriangleup c \\ j_{H_2O}=\frac{0.25}{0.15} \times 8.64 \times 10^{-6} \\ j_{H_2O}=14.4 \times 10^{-6} cm/s$

For calculation of water level drop in a day, converting mass flux as

$j_{H_2O}=14.4 \times 10^{-6} \times 24 \times 3600 cm/day\\ j_{H_2O}=1.24 cm/day$

So the water level will drop by about 1.24 cm in 1 day.

7 0

4 years ago

Find the direction of this vector

Alika [10]

Answer:

125 degrees

Explanation:

180 - 55 = 125 degrees

8 0

2 years ago

A physicist comes across an open container which is filled with two liquids. Since the two liquids have different density, there

Dominik [7]

Answer:

496.57492 kg/m³

Explanation:

$P_a$ = Atmospheric pressure = 101300 Pa

$\rho_w$ = Density of water = 1000 kg/m^3

$h_w$ = Height of water = 21.8 cm

$h_f$ = Height of fluid = 30 cm

g = Acceleration due to gravity = 9.81 m/s²

$\rho_f$ = Density of the unknown fluid

Absolute pressure at the bottom

$P_{abs}=P_a+\rho_wgh_w+\rho_fgh_f\\\Rightarrow \rho_f=\frac{P_{abs}-P_a-\rho_wgh_w}{gh_f}\\\Rightarrow \rho_f=\frac{104900-101300-1000\times 9.81\times 0.218}{9.81\times 0.3}\\\Rightarrow \rho_f=496.57492\ kg/m^3$

The density of the unknown fluid is 496.57492 kg/m³

6 0

3 years ago

How long is an open-open pipe if the fundamebntal frequency is 60Hz. (Hint: Speed of Sound in the Air is 340m/s)

kifflom [539]

Fundamental frequency, f1=v/2l

Let the length of the pipe be ‘l’

By given: v=340m/s, f1=60Hz

Thus, 60=340/2l

60=170/l

l=170/60=17/6=2.8333

The length of the pipe is 17/3=2.8333m.

3 0

3 years ago