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3 years ago

How long is a red blood cell

1 answer:

7 0

I suspect this question should read "How long does a red blood cell live." A red blood cell lives for between 100 and 120 days. It takes 7 days for a new red blood cell to develop from stem cells. Stem cells are similar to base cells. They can also be seen as a general template from which specialized cells are made. Stem cells can be taken from a newborn baby's umbilical chord or extracted from an adult blood donor's blood.This

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A freezer compartment is covered with a 2-mm-thick layer of frost at the time it malfunctions. If the compartment is in ambient

ruslelena [56]

Answer:

The time required to melt the frost is 3.25 hours.

Explanation:

The time required to melt the frost dependes on the latent heat of the frost and the amount of heat it is transfered by convection to the air .

The heat transferred per unit area can be expressed as:

$q=h_c*A*\Delta T\\\\q/A=h_c*\Delta T$

being hc the convective heat transfer coefficient (2 Wm^-2K^-1) and ΔT the difference of temperature (20-0=20 °C or K).

$q/A=h_c*\Delta T=2\frac{W}{m^2K}*20K=40\frac{W}{m^2}$

If we take 1 m^2 of ice, with 2 mm of thickness, we have this volume

$V=T*A = 0.002 m * 1 m^2=0.002m^3$

The mass of the frost can be estimated as

$M=\rho * V=700\frac{kg}{m^3}*0.002m^3= 1.4 kg$

Then, the amount of heat needed to melt this surface (1 m²) of frost is

$Q=L*M=334\frac{kJ}{kg}*1.4kg= 467.6kJ$

The time needed to melt the frost can be calculated as

$t=\frac{Q}{(q/A)}=\frac{467.6kJ/m2}{40W/m2} = 11.69\frac{kJ}{W}*\frac{1W*s}{1J}*\frac{1000J}{1kJ}= 11690s=3.25h$

7 0

3 years ago

Soda pop is carbonated with CO2. Mark puts one bottle of soda pop in the refrigerator and leaves the other out in the hot sunlig

fomenos

Answer:

The one left in the hot sunlight.

Explanation:

The solubility of gases decreases when temperature increases. The gas in the soda pop (CO2) left in the sun will not stay dissolved as much as the on left in the refrigerator.

3 0

2 years ago

What are the 5 ways to identify if a chemical reaction happened?

vlada-n [284]

Answer:

a new substance is formed, if heat is formed, color change, the evolution of gas, and bubbles or fizzing

7 0

3 years ago

Which element are in the compound CoCI2?<br><br> Choose all correct answers.

Kobotan [32]

Answer:

the answer is cobalt and chloride

7 0

2 years ago

Read 2 more answers

jelani and Mikah are watching an approaching storm from their living room window. All of a sudden they see a bright flash of lig

Shtirlitz [24]

Answer: Heat causes surrounding air to rapidly expand and vibrate, which creates the pealing thunder we hear a short time after seeing a lightning flash.

4 0

3 years ago