answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Oxana [17]
2 years ago
14

A wind turbine with a rotor diameter of 40 m produces 90 kW of electrical power when the wind speed is 8 m/s. The density of air

impinging on the turbine is 1.2 kg/m3. What fraction of the kinetic energy of the wind impinging on the turbine is converted to electrical energy
Physics
1 answer:
aleksley [76]2 years ago
8 0

Answer:

0.233

Explanation:

Given that

Diameter of rotor, d = 40 m

Power of rotor, P = 90 kW

Speed of the wind, v = 8 m/s

Density of air, p = 1.2 kg/m³

It is a known fact that

KE = ½mv², where mass flow rate, m

m = p.A.v, where Area, A

A = πd²/4

A = (3.142 * 40²)/4

A = 3.142 * 1600/4

A = 3.142 * 400

A = 1256.8 m², substitute for A in the mass flow rate equation

m = p.A.v

m = 1.2 * 1256.8 * 8

m = 12065.28, substitute for m in the KE equation

KE = ½mv²

KE = ½ * 12065.28 * 8²

KE = 12065.28 * 32

KE = 386088.96 W or

KE = 386.1 kW

Fraction of kinetic energy converted to electric energy is

Fraction = Electric Power / Total KE

Fraction = 90 / 386.1

Fraction = 0.233

You might be interested in
A snowball is melting at a rate of 324π mm3/s. At what rate is the radius decreasing when the volume of the snowball is 972π mm3
Oduvanchick [21]

Answer:

The radius is decreasing at 4 mm/s

Explanation:

The volume of a sphere is:

V = 4/3*\pi *r^3   So, when the volume is 972π mm^3 the radius r is:

r = 9mm

Now, the change rate is given by the derivative:

dV/dt = 4/3*\pi *3*r^2*dr/dt  

Where: dV/dt = -324π mm^2/s

            r = 9mm

Solving for dr/dt:

dr/dt = -4mm/s

5 0
2 years ago
Two marbles are launched at t = 0 in the experiment illustrated in the figure below. Marble 1 is launched horizontally with a sp
Alex787 [66]

Answer:

Two marbles are launched at t = 0 in the experiment illustrated in the figure below. Marble 1 is launched horizontally with a speed of 4.20 m/s from a height h = 0.950 m. Marble 2 is launched from ground level with a speed of 5.94 m/s at an angle above the horizontal. (a) Where would the marbles collide in the absence of gravity? Give the x and y coordinates of the collision point. (b) Where do the marbles collide given that gravity produces a downward acceleration of g = 9.81 m/s2? Give the x and y coordinates.

Explanation:

i want the answer i don't know

7 0
2 years ago
Read 2 more answers
A person walks 25 m west and then 45 m at the angle of 60 degrees north of east what is the magnitude of the total displacement?
expeople1 [14]


To solve this question, we need to use the component method and split our displacements into their x and y vectors. We will assign north and east as the positive directions.

The first movement of 25m west is already split. x = -25m, y = 0m.

The second movement of 45m [E60N] needs to be split using trig.
x = 45cos60 = 22.5m
y = 45sin60 = 39.0m

Then, we add the two x and two y displacements to get the total displacement in each direction.

x = -25m + 22.5m = -2.5m
y = 0m + 39.0m

We can use Pythagorean theorem to find the total displacement.
d² = x² + y²
d = √(-2.5² + 39²)
d = 39.08m

And then we can use tan to find the angle.
inversetan(y/x) = angle
inversetan(39/2.5) = 86.3

Therefore, the total displacement is 39.08m [W86.3N]

8 0
2 years ago
You are driving on a road where rain has left large pools of water, and you have driven through water that was several inches de
makvit [3.9K]
In would say that you may have water in your brakes which may have gotten in the brake lines or in the brake discs so that could cause the brakes to malfunction due to driving through the pools of water so the brakes should be examined as soon as possible.
3 0
2 years ago
Read 2 more answers
A fireman clings to a vertical ladder and directs the nozzle of a hose horizontally toward a burning building. The rate of water
Aleks [24]

Answer:

A torque of 102.5375 Nm must be exerted by the fireman

Explanation:

Given:

The rate of water flow = 6.31 kg/s

The speed of nozzle  = 12.5 m/s

Now, from the Newton's second law we have  

The reaction force to water being redirected horizontally (F) = rate of change of water's momentum in the horizontal direction

thus we have,

F = 6.31 kg/s x 12.5m/s

or

F = 78.875 N  

Now,

The torque (T) exerted by water force about the fireman's will be

T = (F x d)

or

T = 78.875 N x 1.30 m

T = 102.5375 Nm

hence,

<u>A torque of 102.5375 Nm must be exerted by the fireman</u>

4 0
2 years ago
Other questions:
  • If the water vapor content of air remains constant, lowering air temperature causes _____.
    8·2 answers
  • Samantha wants to study circus performance when she gets to college. She has mastered many physical skills already, but she keep
    6·2 answers
  • A bullet is fired through a board, 14.0 cm thick, with its line of motion perpendicular to the face of the board. if it enters w
    7·2 answers
  • Step 8: Observe How Changes in the Speed of the Bottle Affect Beanbag Height
    7·2 answers
  • 1) A star burst can be defined as stars formed from recycled dead star materials.
    10·1 answer
  • A satellite is in circular orbit at an altitude of 1500 km above the surface of a nonrotating planet with an orbital speed of 9.
    11·1 answer
  • Michael Phelps needs to swim at an average speed of 2.00 m/s in order to set a new world record in the 200 m freestyle. If he sw
    8·1 answer
  • Consider two adjacent states, S1 and S2, that wish to control particulate emissions from power plants and cement plants; New Jer
    14·1 answer
  • To store stacks of clean plates, a cafeteria uses a closed cart with a spring-loaded shelf inside. Customers can take plates off
    12·1 answer
  • A submarine completed a 450 km training with an average speed of 50 km/h. For the first 180 km, it travelled at an average speed
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!