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3 years ago

Brainliest!!! need help

1 answer:

5 0

I got an electric shock when I was a baby by chewing on a cable and I also got another electric shock by plugging my phone in

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A spherical balloon with a diameter of 9 m is filled with helium at 20°C and 200 kPa. Determine the mole number and the mass of

SIZIF [17.4K]

Answer:

number of mole is 31342.36 moles

mass is 125.369 kg

Explanation:

Diameter of the spherical balloon d = 9 m

radius r = d/2 = 9/2 = 4.5 m

The volume pf the sphere balloon ca be calculated from

V = $\frac{4}{3} \pi r^3$

V = $\frac{4}{3}* 3.142* 4.5^3$ = 381.75 m^3

Temperature of the gas T = 20 °C = 20 + 273 = 293 K

Pressure of the helium gas = 200 kPa = 200 x 10^3 Pa

number of moles n = ?

Using

PV = nRT

where

P is the pressure of the gas

V is the volume of the gas

n is the mole number of the gas

R is the gas constant = 8.314 m^3⋅Pa⋅K^−1⋅mol^−1

T is the temperature of the gas (must be converted to kelvin K)

substituting values, we have

200 x 10^3 x 381.75 = n x 8.314 x 293

number of moles n = 76350000/2436 = 31342.36 moles

We recall that n = m/MM

or m = n x MM

where

n is the number of moles

m is the mass of the gas

MM is the molar mass of the gas

For helium, the molar mass = 4 g/mol

substituting values, we have

m = 31342.36 x 4

m = 125369.44 g

m = 125.369 kg

3 0

3 years ago

A closed, 0.4-m-diameter cylindrical tank is completely filled with oil (SG 0.9)and rotates about its vertical longitudinal axis

egoroff_w [7]

Answer: $p_{B} - p_{A}$ = 28800 Pa or 28.8 kPa

Explanation: To determine the pressure of a liquid in a rotating tank,it is used:

p = $\frac{p_{fluid}.w^{2}.r^{2} }{2}$ - γfluid . z + c

where:

$p_{fluid}$ is the liquid's density

w is the angular velocity

r is the radius

γfluid.z is the pressure variation due to centrifugal force.

For this question, the difference between a point on the circumference and a point on the axis will be:

$p_{B} - p_{A}$ = $\frac{p_{fluid}.w^{2}.r_{B} ^{2} }{2}$ - γfluid. $z_{B}$ - ( $\frac{p_{fluid}.w^{2}.r_{A} ^{2} }{2}$ - γfluid. $z_{A}$ )

$p_{B} - p_{A}$ = $\frac{p_{fluid}.w^{2}}{2} (r_B^{2} - r_A^{2} )$ - γfluid( $z_{B}$ - $z_{A}$ )

Since there is no variation in the z-axis, z = 0 and that the density of oil is 0.9.10³kg/m³:

$p_{B} - p_{A}$ = $\frac{p_{fluid}.w^{2}}{2} (r_B^{2} - r_A^{2} )$

$p_{B} - p_{A} = \frac{0.9.10^3.40^2}{2}(0.2^2 - 0)$

$p_{B} - p_{A}$ = 28800

The difference in pressure between two points, one on the circumference and the other on the axis is $p_{B} - p_{A}$ = 28800 Pa or 28.8 kPa

8 0

3 years ago

A parallel circuit with two branches and an 18 volt battery. Resistor #1 on the first branch has a value of 220 ohms and resisto

likoan [24]

Answer:

2.455 W

Explanation:

The power dissipated in each branch is ...

P = V^2/R

So, the branch powers are ...

branch 1: 18^2/220 ≈ 1.473 W

branch 2: 18^2/330 ≈ 0.982 W

Total power is ...

1.473 W + 0.982 W = 2.455 W

8 0

3 years ago

Select the correct answer.

Genrish500 [490]

A is the correct answer

5 0

3 years ago

2.11 Consider a 400 mm × 400 mm window in an aircraft. For a temperature difference of 90°C from the inner to the outer surface

alexandr402 [8]

Answer:

The heat loss rate through one of the windows made of polycarbonate is 252W. If the window is made of aerogel, the heat loss rate is 16.8W. If the window is made of soda-lime glass, the heat loss rate is 1190.4W.

The cost associated with the heat loss through the windows for an 8-hour flight is:

For aerogel windows: $17.472 (most efficient)

For polycarbonate windows: $262.08

For soda-lime glass windows: $1,238.016 (least efficient)

Explanation:

To calculate the heat loss rate through the window, we can use a model of heat transmission by conduction throw flat wall. Using unidimensional Fourier law:

$\frac{dQ}{dt}=\dot Q =-kS\nabla \vec{T}$

In this case:

$\dot Q =k\frac{S}{L} \Delta T$

If we replace the data provided by the problem we get the heat loss rate through one of the windows of each material (we only have to change the thermal conductivities).

To obtain the thermal conductivity of the soda-lime glass we use the graphic attached to this answer (In this case for soda-lime glass k₃₀₀=0.992w/m·K).

To calculate the cost associated with the heat loss through the windows for an 8-hour flight we use this formula (using the heat loss rate calculated in each case):

$Cost=C_{hc}\cdot \dot Q \cdot t \cdot n=1\frac{\$}{Kwh} \cdot \dot Q \cdot 8h \cdot 130$

6 0

3 years ago