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3 years ago

5 uses of mechanical energy

Physics

1 answer:

Oksi-84 [34.3K]3 years ago

8 0

Answer: The 5 uses of mechanical energy are: 1) Hammering a nail

2) Using Dart gun 3) Moon 4) Hydropower plant 5) Sharping a pencil.

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Name one reason why you should pour milk in before cereal.

krok68 [10]

Answer:

splashing

Explanation:

if you put in the cereal after the milk it will splash everywhere, causing a waste of milk, and a loss of time.

5 0

3 years ago

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

Mariulka [41]

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.

5 0

3 years ago

What is the wavelength

melamori03 [73]

The distance between two particles that are <em>in phase</em>

4 0

3 years ago

What is the movement of a stationary object?

galben [10]

If it is stationary, its not moving. there is no movement

8 0

4 years ago

A person travels from New York to Washington at the rate of 45 km per hour and

mr_godi [17]

Answer:

The average speed for the whole journey is 49.5 miles per hour.

Explanation:

Step 1 :

Here, both the ways, he covers the same distance. Then, the formula to find average speed is

= 2xy / (x+y)

Step 2 :

x ----> Rate at which he travels from New York to Washington

x = 45

y ----> Rate at which he travels from New York to Washington

y = 55

Step 3 :

So, the average speed is

= (2 ⋅ 45 ⋅ 55) / (45 + 55)

= 4950 / 100

= 49.5

8 0

3 years ago

5 uses of mechanical energy​

5 uses of mechanical energy