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3 years ago

15

Scientists use characteristics to compare stars. Match each characteristic on the left with the statement on the right that uses

it to compare stars.

1 answer:

Llana [10]3 years ago

8 0

Answer:

Explanation:

some are bigger and some are smaller

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Sarah is developing a Risk Assessment for her organization. She is asking each department head how long can they be without thei

Natali [406]

Answer:

Sarah is asking each department head how long they can be without their primary system. Sarah is trying to determine the Recovery Time Objective (RTO) as this is the duration of time within which the primary system must be restored after the disruption.

Recovery Point Objective is basically to determine the age of restoration or recovery point.

Business recovery and technical recovery requirements are to assess the requirements to recover by Business or technically.

Hence, Recovery Time Objective (RTO) is the correct answer.

8 0

3 years ago

EMB agar is a medium used in the identification and isolation of pathogenic bacteria. It contains digested meat proteins as a so

Ilya [14]

Answer:

A selective medium, a differential medium, and a complex medium.

Explanation:

A selective media is a microbiological media which only support the growth of a particular specie or types of species of microorganisms,this media acts in such a way to inhibit or hinder the growth of other microorganisms.

Differential media are media that acts to Identifying particular strains of microorganisms of similar species.

Complex media are media used for the growth of microorganisms this which contains complex or a wide range of nutrients with chemical composition which may be difficult to determine.

5 0

3 years ago

Some of our modern kitchen cookware is made of ceramic materials. (a) List at least three important characteristics required of

Alisiya [41]

Answer:

A)

It should be Non- toxic

It should possess high Thermal conductivity

It should have the Required Thermal diffusivity

B)

stoneware : This material has good thermal diffusivity and it is quite affordable and it is used in making pizza stones
porcelain: mostly used for mugs and it is non-toxic
Pyrex : posses good thermal conductivity used in oven

C) All the materials are suitable because they serve different purposes when making modern kitchen cookware

Explanation:

A) characteristics required of a ceramic material to be used as a kitchen cookware

It should be Non- toxic
It should possess high Thermal conductivity
It should have the Required Thermal diffusivity

B) comparison of three ceramic materials as to their relative properties

stoneware : This material has good thermal diffusivity and it is quite affordable and it is used in making pizza stones
porcelain: mostly used for mugs and it is non-toxic
Pyrex : posses good thermal conductivity used in ovens

C) material most suitable for the cookware.

All the materials are suitable because they serve different purposes when making modern kitchen cookware

8 0

2 years ago

Water at atmospheric pressure boils on the surface of a large horizontal copper tube. The heat flux is 90% of the critical value

masya89 [10]

Answer:

The tube surface temperature immediately after installation is 120.4°C and after prolonged service is 110.8°C

Explanation:

The properties of water at 100°C and 1 atm are:

pL = 957.9 kg/m³

pV = 0.596 kg/m³

ΔHL = 2257 kJ/kg

CpL = 4.217 kJ/kg K

uL = 279x10⁻⁶Ns/m²

KL = 0.68 W/m K

σ = 58.9x10³N/m

When the water boils on the surface its heat flux is:

$q=0.149h_{fg} \rho _{v} (\frac{\sigma (\rho _{L}-\rho _{v})}{\rho _{v}^{2} } )^{1/4} =0.149*2257*0.596*(\frac{58.9x10^{-3}*(957.9-0.596) }{0.596^{2} } )^{1/4} =18703.42W/m^{2}$

For copper-water, the properties are:

Cfg = 0.0128

The heat flux is:

qn = 0.9 * 18703.42 = 16833.078 W/m²

$q_{n} =uK(\frac{g(\rho_{L}-\rho _{v}) }{\sigma })^{1/2} (\frac{c_{pL}*deltaT }{c_{fg}h_{fg}Pr } \\16833.078=279x10^{-6} *2257x10^{3} (\frac{9.8*(957.9-0.596)}{0.596} )^{1/2} *(\frac{4.127x10^{3}*delta-T }{0.0128*2257x10^{3}*1.76 } )^{3} \\delta-T=20.4$

The tube surface temperature immediately after installation is:

Tinst = 100 + 20.4 = 120.4°C

For rough surfaces, Cfg = 0.0068. Using the same equation:

ΔT = 10.8°C

The tube surface temperature after prolonged service is:

Tprolo = 100 + 10.8 = 110.8°C

8 0

3 years ago

The Torricelli's theorem states that the (velocity—pressure-density) of liquid flowing out of an orifice is proportional to the

Sergeeva-Olga [200]

Answer:

The correct answer is 'velocity'of liquid flowing out of an orifice is proportional to the square root of the 'height' of liquid above the center of the orifice.

Explanation:

Torricelli's theorem states that

$v_{exit}=\sqrt{2gh}$

where

$v_{exit}$ is the velocity with which the fluid leaves orifice

$h$ is the head under which the flow occurs.

Thus we can compare the given options to arrive at the correct answer

Velocity is proportional to square root of head under which the flow occurs.

4 0

3 years ago