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Lapatulllka [165]

4 years ago

14

A fan is to accelerate quiescent air to a velocity of 8 m/s at a rate of 9 m3 /s. determine the minimum power that must be suppl

ied to the fan. take the density of air to be 1.18 kg/m3

1 answer:

ELEN [110]4 years ago

8 0

Given:
ρ = 1.18 kg/m³, density of air
v = 8 m/s, flow velocity
Q = 9 m³/s, volumetric flow rate

The minimum power required (at 100% efficiency) is
$\frac{1}{2} (8 \, \frac{m}{s} )^{2}*(9 \, \frac{m^{3}}{s} )*(1.18 \, \frac{kg}{m^{3}}) = 339.84 \, W$

The actual power will be higher because 100% efficiency is not possible.

Answer: 339.8 W (nearest tenth)

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The compass of an airplane indicates that it is headed due north and its airspeed indicator shows that it is moving through the

yarga [219]

Answer:

Airplane speed relative to the ground is 260 km/h and θ = 22.6º direction from north to east

Explanation:

This is a problem of vector composition, a very practical method is to decompose the vectors with respect to an xy reference system, perform the sum of each component and then with the Pythagorean theorem and trigonometry find the result.

Let's take the north direction with the Y axis and the east direction as the X axis

Vy = 240 km / h airplane

Vx = 100 Km / h wind

a) See the annex

Analytical calculation of the magnitude of the speed and direction of the aircraft

V² = Vx² + Vy²

V = √ (240² + 100²)

V = 260 km/h

Airplane speed relative to the ground is 260 km/h

Tan θ = Vy / Vx

tan θ = 100/240

θ = 22.6º

Direction from north to eastb

b) What direction should the pilot have so that the resulting northbound

Vo = 240 km/h airplane

Vox = Vo cos θ

Voy = Vo sin θ

Vx = 100 km / h wind

To travel north the speeds the x axis (East) must add zero

Vx -Vox = 0

Vx = Vox = Vo cos θ

100 = 240 cos θ

θ = cos⁻¹ (100/240)

θ = 65.7º

North to West Direction

The speed in that case would be

V² = Vx² + Vy²

To go north we must find Vy

Vy² = V² - Vx²

Vy = √( 240² - 100²)

Vy = 218.2 km / h

8 0

4 years ago

which obstacle to problem solving involves arriving at a solution based on your preconceptions and ignoring any evidence that go

White raven [17]

Answer:

confirmation bias

Explanation:

the tendency to interpret new evidence as confirmation of one's existing beliefs or theories in a way that affirms one's prior beliefs or hypotheses.

5 0

4 years ago

Your fitness tracker tells you that you have delivered 124 kJ of work during your workout. The tracker also shows that you have

REY [17]

To solve this problem, we must basically count the total energy lost converting all the values given in the international system.

The energy loss is given by both 124KJ and 124food heats.

Since the energy conversion we know that 1 food calories is equal to 4,184J. So:

$124 calories (\frac{4.184J}{1 calories}) = 518.816J = 0.518816kJ$

Therefore the total energy lost will be

$E_{lost} = 124 KJ + 0.518816 KJ$

$E_{lost} = 124.518KJ$

Therefore the total energy lost to the surroindings in form of heat is 124.518kJ

3 0

3 years ago

A light string is wrapped around the outer rim of a solid uniform cylinder of diameter 75.0 cm that can rotate without friction

anyanavicka [17]

Answer:18.5 kg

Explanation:

Given

diameter $d=75 cm$

mass of stone $m=3 kg$

velocity of stone $v=3.4 m/s$

height fallen $h=2.40 m$

using

$v^2-u^2=2as$

$(3.4)^2=2\times a\times 2.4$

$a=2.4 m/s^2$

Tension of string will Provide Torque to cylinder

$T\times r=I\times \alpha$

where $I=moment\ of\ inertia$

$\alpha =angular\ acceleration$

$T=\frac{Mr^2}{2}\times \frac{a}{r}$

$T=\frac{Ma}{2}$

and $mg-T=ma$

$mg-ma=T$

Put value of T

$mg-ma=\frac{Ma}{2}$

$mg=a(m+\frac{M}{2})$

$3\times 9.8=2.4\cdot (m+\frac{M}{2})$

$12.25=3+\frac{M}{2}$

$9.25=\frac{M}{2}$

$M=18.5 kg$

4 0

4 years ago

When a police officer receives information that you are speeding in your vehicle, she is using the ______________ of the wave to

Alex

I think the corect answer would be C. When a police officer receives information that you are speeding in your vehicle, she is using the frequency of the wave to measure the Doppler Effect. As the speed of a vehicle increases, the greater the change of the frequency of the waves would be transmitted to the radar guns which is being used by the police officer. Doppler effect is an effect that is observed in sound and light waves as these waves move away or to the direction of the observer. This is being used in many applications like in astronomy, weather balloons, the radar guns,and for underwater researches.

6 0

3 years ago