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motikmotik
3 years ago
11

A desktop computer is to be cooled by a fan whose flow rate is 0.34 m3 /min. Determine the mass flow rate of air through the fan

at an elevation of 3400 m where the air density is 0.7 kg/m3 . Also, if the average velocity of air is not to exceed 110 m/min, determine the diameter of the casing of the fan. (Page 215).
Engineering
1 answer:
Aleks [24]3 years ago
3 0

Answer:

m = 0.238  <u>kg</u>

                  min

r = 0.063m

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What is 1000J in Btu?
dybincka [34]

Answer:

0.948 Btu

Explanation:

1 Btu = 1055 J so \frac{1000}{1055} = 0.948 Btu

5 0
4 years ago
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A steel cylindrical pressure vessel has an inside diameter of 2m and a wall thickness of 2cm. If the steel has a yield stress Y
Feliz [49]

Answer:

The pressure that will cause yielding in the tank in the longitudinal direction is 1.7 Mpa

Explanation:

We are dealing with a thin-walled pressure vessel here.

the formula for calculating the hoops stress of this pressure vessel is \sigma =P d/4t

\sigma Y = longitudinal yield stress = 425  \times 10^{6} Pa

Thickness = 2/1000 =0.002m

Outside diameter = inside siameter + thickness =  2m + 0.002m= 2.002m

Dm = Mean diameter = Outside diameter - thickness = 2.002 - 0.002 = 2m

P= 425 \times 10^{6} \times 4 \times 0.002 /2=1.7 Mpa

4 0
3 years ago
The contents of a tank are to be mixed with a turbine impeller that has six flat blades. The diameter of the impeller is 3 m. If
lions [1.4K]

Answer:

P=3.31 hp (2.47 kW).

Explanation:

Solution

Curve A in Fig1. applies under the conditions of this problem.

S1 = Da / Dt ; S2 = E / Dt ; S3 = L / Da ; S4 = W / Da ; S5 = J / Dt and S6 = H / Dt

The above notations are with reference to the diagram below against the dimensions noted. The notations are valid for other examples following also.

32.2

Fig. 32.2 Dimension of turbine agitator

The Reynolds number is calculated. The quantities for substitution are, in consistent units,

D a =2⋅ft

n= 90/ 60 =1.5 r/s

μ = 12 x 6.72 x 10-4 = 8.06 x 10-3 lb/ft-s

ρ = 93.5 lb/ft3 g= 32.17 ft/s2

NRc = (( D a) 2 n ρ)/ μ = 2 2 ×1.5×93.5 8.06× 10 −3 =69,600

From curve A (Fig.1) , for NRc = 69,600 , N P = 5.8, and from Eq. P= N P × (n) 3 × ( D a )5 × ρ g c

The power P= 5.8×93.5× (1.5) 3 × (2) 5 / 32.17 =1821⋅ft−lb f/s requirement is 1821/550 = 3.31 hp (2.47 kW).

5 0
3 years ago
A motor vehicle has a mass of 1.8 tonnes and its wheelbase is 3 m. The centre of gravity of the vehicle is situated in the centr
seropon [69]

Answer:

1) The normal reactions at the front wheel is 9909.375 N

The normal reactions at the rear wheel is 8090.625 N

2) The least coefficient of friction required between the tyres and the road is 0.625

Explanation:

1) The parameters given are as follows;

Speed, u = 90 km/h = 25 m/s

Distance, s it takes to come to rest = 50 m

Mass, m = 1.8 tonnes = 1,800 kg

From the equation of motion, we have;

v² - u² = 2·a·s

Where:

v = Final velocity = 0 m/s

a = acceleration

∴ 0² - 25² = 2 × a × 50

a = -6.25 m/s²

Force, F =  mass, m × a = 1,800 × (-6.25) = -11,250 N

The coefficient of friction, μ, is given as follows;

\mu =\dfrac{u^2}{2 \times g \times s} = \dfrac{25^2}{2 \times 10 \times 50} = 0.625

Weight transfer is given as follows;

W_{t}=\dfrac{0.625 \times 0.9}{3}\times \dfrac{6.25}{10}\times 18000 = 2109.375 \, N

Therefore, we have for the car at rest;

Taking moment about the Center of Gravity CG;

F_R × 1.3 = 1.7 × F_F

F_R + F_F = 18000

F_R + \dfrac{1.3 }{1.7} \times  F_R = 18000

F_R = 18000*17/30 = 10200 N

F_F = 18000 N - 10200 N = 7800 N

Hence with the weight transfer, we have;

The normal reactions at the rear wheel F_R  = 10200 N - 2109.375 N = 8090.625 N

The normal reactions at the front wheel F_F =  7800 N + 2109.375 N = 9909.375 N

2) The least coefficient of friction, μ, is given as follows;

\mu = \dfrac{F}{R} =  \dfrac{11250}{18000} = 0.625

The least coefficient of friction, μ = 0.625.

3 0
4 years ago
A lake with constant volume 1.1 x 10^6 m^3 is fed by a stream with a non-conservative pollutant of 2.3 mg/L and flow rate 35 m^3
Jet001 [13]

Answer:

12.84 mg/L

Explanation:

We are given;

Volume of lake; V = 1.1 x 10^(6) m³

decay coefficient; K = 0.10/day = 0.1/(24 × 60 × 60) /s = 0.00000115741 /s

Factory rate: Q_f = 4.3 m³/s

Factory concentration: C_f = 100 mg/L

Stream rate: Q_s = 34 m³/s

Stream Concentration: C_s = 2.3 mg/L

Now, to find the steady state concentration of pollutant in the lake, we will use the formula;

(Q_s•C_s) + (Q_f•C_f) = (Q_f + Q_s)C_L + (KV•C_L)

Where C_L is the steady state concentration of pollutant in the lake.

Thus, making C_L the subject, we have;

C_L = [(Q_s•C_s) + (Q_f•C_f)]/(Q_f + Q_s + K•V)

Plugging in the relevant values gives;

C_L = ((34 × 2.3) + (4.3 × 100))/(4.3 + 34 + (0.00000115741 × 1.1 × 10^(6)))

C_L = 12.84 mg/L

4 0
3 years ago
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