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2 years ago

Randy wants to know whether a soil's porosity affects how easily seedlings grow in it.

2 answers:

4 0

Since the main objective of this experiment is to determine the effect of porosity on seedling growth that should be the only independent variable. In short, that is the only variable that should be different to ensure fair testing.

The answer should be B:

he plants seedlings in soils with different levels of porosity and equal levels of permeability.

Permeability is not what needs to be tested. If it changes, you may not be able to determine whether it was the porosity or permeability that cause changes.

Masteriza [31]2 years ago

3 0

Answer: B: different, equal

Explanation:

Since Randy wants to know how porosity affects seedling growth, he needs to design an experiment in which he uses soils of different porosity but keeps everything else the same. This means that his experiment should involve soils with equal levels of permeability, since this factor can also affect seedling growth. Randy is likely to find that most seedlings succeed in porous soils, because the open spaces between particles give them room to grow.

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A 30-km, 34.5-kV, 60-Hz, three-phase line has a positive-sequence series impedance z 5 0.19 1 j0.34 V/km. The load at the receiv

zmey [24]

Answer:

(a) With a short line, the A,B,C,D parameters are:

A = 1pu B = 1.685∠60.8°Ω C = 0 S D = 1 pu

(b) The sending-end voltage for 0.9 lagging power factor is 35.96 $KV_{LL}$

Explanation:

(a)

Considering the short transition line diagram.

Apply kirchoff's voltage law to the short transmission line.

Write the equation showing the relations between the sending end and the receiving end quantities.

Compare the line equations with the A,B,C,D parameter equations.

(b)

Determine the receiving-end current for 0.9 lagging power factor.

Determine the line-to-neutral receiving end voltage.

Determine the sending end voltage of the short transition line.

Determine the line-to-line sending end voltage which is the sending end voltage.

(c)

Determine the receiving-end current for 0.9 leading power factor.

Determine the sending-end voltage of the short transition line.

Determine the line-to-line sending end voltage which is the sending end voltage.

8 0

2 years ago

In Physics lab, Ellen has been given the task of constructing a simple motor. She must find common household items at home and b

Aleks [24]

Answer:

a) battery-->electrical current-->copper wire rotor -->magnet--> mechanical energy

Explanation:

6 0

2 years ago

Read 2 more answers

A rocket in deep space has an exhaust-gas speed of 2000 m/s. When the rocket is fully loaded, the mass of the fuel is five times

notka56 [123]

Answer:

$v_{f}$ = 1,386 m / s

Explanation:

Rocket propulsion is a moment process that described by the expression

$v_{f}$ - v₀ = $v_{r}$ ln (M₀ / Mf)

Where v are the velocities, final, initial and relative and M the masses

The data they give are the relative velocity (see = 2000 m / s) and the initial mass the mass of the loaded rocket (M₀ = 5Mf)

We consider that the rocket starts from rest (v₀ = 0)

At the time of burning half of the fuel the mass ratio is that the current mass is

M = 2.5 Mf

$v_{f}$ - 0 = 2000 ln (5Mf / 2.5 Mf) = 2000 ln 2

$v_{f}$ = 1,386 m / s

3 0

2 years ago

1. Describe the methods by which an electric potential develops in primary cells and dry cells.

Andreyy89

Answer:

In primary cells, an electric potential develops through chemical action between the plates within the cell. Positively charged ions of zinc enter the acid and free electrons released from zinc atoms collect on the zinc plate, which results in a negative charge. At the same time, positively charged ions of hydrogen from the acid remove free electrons from the copper plate, which becomes positively charged. Through a conducting material connecting the plates, free electrons move from the zinc plate to the copper plate as long as the chemical reaction lasts.

Dry cells also develop electric potential via chemical actions within the cell. Free electrons removed from the carbon rod collect on a zinc can. The rod exhibits a positive charge and the can becomes negatively charged; this allows for an electric potential to develop between these two items. Through a conducting material connecting the can to the rod, free electrons move from the can to the rod as long as the conducting path exists.

Electric generators develop an electric potential via magnetic induction. Moving a conducting rod through a magnetic field that exists between the poles of a horseshoe magnet causes an electric potential to be set up in the rod. Free electrons move through this rod from one end to the other for as long as movement of the rod is maintained. The direction of this movement depends on whether the rod is moved across the lines of force in the magnetic field in either the opposite direction or the same direction. Generators usually consist of multiple conductors mounted on a cylinder that rotates in a magnetic field.

Thermocouples utilize heat to develop an electric potential. Two strips of different metals are connected at one end to form a junction and the other ends are kept apart. A heat source is applied to the junction; this causes each metal strip’s temperature to rise at the junction. The free ends aren’t as hot and electric charges are produced at these free ends. Because the strips consist of different materials, there's a difference of potential between these free ends; when connected by a conducting wire, the electrons can move through the pathway. The voltage that's produced will become greater as the difference in temperature between the free ends and the junction increases.

a. Increase

b. Decrease

c. Decrease

Since 1 Btu = 0.293 Wh, dividing the given amount of Wh by 0.293 will convert this amount into Btu. Therefore, 0.8 ÷ 0.293 = 2.73 Btu

365 days × 10 hours × 40 W = 146,000 Wh or 146 kWh

Explanation:

Penn Foster

6 0

2 years ago

A green laser pointer has a wavelength of 532 nm. what is the energy of one mol of photons generated from this device?

PSYCHO15rus [73]

We have energy E = hc/λ, where h is Planck's constant c is speed of light and λ is the wavelength.

So Energy , $E=\frac{6.63*10^{-34}*3*10^8}{532*10^{-9}} =3.73*10^{-19}J$

Energy of one mol = $3.73*10^{-19}*6.023*10^{23}=225 kJ/mol$

Energy of one mol of photons generated from this device = 225 kJ

3 0

2 years ago