1answer.
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
tangare [24]
3 years ago
6

Determine the power that needs to besupplied by the fanifthe desired velocity is 0.05 m3/s and the cross-sectional area is 20 cm

Physics
1 answer:
Mariulka [41]3 years ago
5 0

Answer:

A fan with an energy efficiency of 30 % would need 62.5 watts to bring a desired volume flow of 0.05 cubic meters per second through a cross-sectional area of 20 square centimeters.

Explanation:

Complete statement is: <em>Determine the power that needs to besupplied by the fan if the desired velocity is 0.05 cubic meters per second and the cross-sectional area is 20 square centimeters.</em>

From Thermodynamics and Fluid Mechanics we know that fans are devices that work at steady state which accelerate gases (i.e. air) with no changes in pressure. In this case, mechanical rotation energy is transformed into kinetic energy. If we include losses due to mechanical friction, the Principle of Energy Conservation presents the following equation:

\eta\cdot \dot W = \dot K

\dot W = \frac{\dot K}{\eta} (Eq. 1)

Where:

\eta - Efficiency of fan, dimensionless.

\dot W - Electric power supplied fan, measured in watts.

\dot K - Rate of change of kinetic energy of air in time, measured in watts.

From definition of kinetic energy, the equation above is now expanded:

\dot W = \frac{\rho_{a}\cdot \dot V}{2\cdot \eta}\cdot \left(\frac{\dot V}{A_{s}} \right)^{2} (Eq. 2)

Where:

\rho_{a} - Density of air, measured in kilograms per cubic meter.

\dot V - Volume flow, measured in cubic meters per second.

A_{s} - Cross-sectional area of fan, measured in square meters.

If we know that \rho_{a} = 1.20\,\frac{kg}{m^{3}}, \dot V = 0.05\,\frac{m^{3}}{s}, \eta = 0.3 and A_{s} = 20\times 10^{-4}\,m^{2}, the power needed to be supplied by the fan is:

\dot K = \left[\frac{\left(1.20\,\frac{kg}{m^{3}} \right)\cdot \left(0.05\,\frac{m^{3}}{s} \right)}{2\cdot (0.3)} \right]\cdot \left(\frac{0.05\,\frac{m^{3}}{s} }{20\times 10^{-4}\,m^{2}} \right)^{2}

\dot K = 62.5\,W

A fan with an energy efficiency of 30 % would need 62.5 watts to bring a desired volume flow of 0.05 cubic meters per second through a cross-sectional area of 20 square centimeters.

You might be interested in
While mowing your lawn, you push a lawnmower 120. m with a constant force of 300. N. How much work have you done, assuming that
Montano1993 [528]
We have: Work done = Force × Displacement
Here, Force = 300 N
Displacement = 120 m

Substitute their values into the formula:
W = 300 × 120 
W = 36000

In scientific notation, it would be: 3.6 × 10⁴

Finally, option C would be your correct answer.

Hope this helps!
3 0
3 years ago
Mary and her younger brother Alex decide to ride the carousel at the State Fair. Mary sits on one of the horses in the outer sec
Alex

Answer:

ωM = 1.7 rad/s

vM = 3.4 m/s

ωA = 1.7 rad/s

vA =  1.7  m/s

Explanation:

Calculation of the angular speed (ω)

We use the following formula for circular motion:

ω = θ / t Formula (1)

Where:

ω: angular speed (rad/s)

θ:angle that the particle travels (rad)

t: time interval (s)

Equivalence

1 revolution = 2π rad

Data

θ= 1 revolution = 2π rad

t = 3.7 s

We replace data in the formula (1):

ω = (2π rad) / (3.7s )= 1.7 rad/s

Because the angular speed depends only on the number of turns in a time interval then Mary's angular speed (ωM) is equal to Alex's angular speed (ωA).

ωM = ωA = 1.7 rad/s

Calculation of the  tangential speed (v)

We use the following formula for circular motion:

v = ω*r  Formula (2)

Where:

v : tangential speed (m/s)

ω: angular speed ( rad/s)

r  : radius of the circular path (m)

Data

ωM = ωM = ω= 1.7 rad/s

rM = 2m  : Mary's circular path radius

rA = 1m :  Alex's circular path radius

We apply the formula (2) to calculate v:

vM = ω* rM = (1.7) (2) = 3.4 m/s

vA = ω* rA = (1.7) (1) =  1.7  m/s

7 0
3 years ago
Carbon-14 is a naturally-occuring, stable isotope that is commonly used is scientific studies as a tracer and to date artifacts.
lina2011 [118]
The answer is that there are 6 electrons, 8 neutrons, and 6 protons in carbon 14. The answer is then, B.
3 0
3 years ago
Read 2 more answers
What is torque in physics ?
irina [24]

Answer:

Torque is a measure of the force that can cause an object to rotate about an axis.

8 0
3 years ago
Read 2 more answers
Two sheets of polarizing material are placed such that their polarizing axes are 90° to each other and no light passes through t
nekit [7.7K]

Answer:

Explanation:

Polarization In this case angle of incidence is not equal to angle of polarization, hence reflected light is partially polarized and transmitted light is also partially polarized.  by reflection is explained by Brewster's law,  

According to this when unpolarized light incident on glass plate at an angle is called as angle of polarizing the reflected light is plane polarized, and transmitted light is partially polarized. The plane of vibration of polarized light is having plane of vibrations perpendicular to plane of incidence.

4 0
3 years ago
Other questions:
  • A light ray is incident on a mirror at an angle θ with respect to the normal. what is the direction of the reflected ray?
    6·1 answer
  • [9]
    10·1 answer
  • F the radius of a sphere is increasing at the constant rate of 2 cm/min, find the rate of change of its surface area when the ra
    11·1 answer
  • S = AD/AT<br> Solve for "AD"
    9·1 answer
  • Here the file attached
    10·2 answers
  • Karen travels 10 mile in 1 hour. How many
    14·1 answer
  • " when striking, the pike, a predatory fish, can accelerate from rest to a speed of 4.0 m/s in 0.11 s."
    5·1 answer
  • If the torque on an object adds up to zero Group of answer choices the object is at rest. the object cannot be turning. the obje
    7·1 answer
  • Heat flows from __________ energy to __________ energy.<br> A. higher, lower<br> B. lower, higher
    10·1 answer
  • Why is brainly so dumb? I am currently trying to get into my account right now, and even though I JUST changed it, it keeps sayi
    6·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!