The characteristic of epithelial cells that makes them ideal for providing this type of protection is that the cells are packed tightly together.
Skin, the body's largest organ,is our first and best defense against external aggressors. The many layers work hard to protect us, however when its condition is compromised, its ability to work as an effective barrier is impaired.

3 0

2 years ago

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A river flows with a speed of 0.600 m/s. A student first swims upriver 0.500 km, then turns around and returns to his starting p

DerKrebs [107]

Answer:

a) 1111.0 seconds

b) 833.3 s

c) Because of proportions

Explanation:

a) Total time of round trip is the sum of time upriver and time downriver

$t_{total}=t_{up}+t_{down}$

Time upriver is calculated with the net speed of student and 0.500 km:

$t_{up}=\frac{d_{istance}}{|v_{swimmer}|} ;\\v_{swimmer}=v_{relative to river}+v_{river}=-1.2+0.6=-0.6 m/s\\t_{up}=\frac{500 m}{0.6 m/s}=833.3 s$

(Becareful with units 0.5 km= 500m) Similarly of downriver:

$t_{down}=\frac{d_{istance}}{|v_{swimmer}|} ;\\v_{swimmer}=1.2+0.6=1.8 m/s\\t_{down}=\frac{500 m}{1.8 m/s}=277.7 s$

So the sum is:

$t_{total}=1111.0s$

b) Still water does not affect student speed, so total time would be simply:

$t_{total}=\frac{1000 m}{1.2 m/s}=833.3 s$

c) For the upriver trip, student moved half the distance in half speed of the calculation in b), so it kept the same ratio and therefore, same time. So the aditional time is actually the downriver.

6 0

2 years ago

A car goes from rest to 40m/s in 5 seconds.<br> What is its acceleration?

attashe74 [19]

Answer:

acceleration is 8 m/s^2

Explanation:

a= final velocity -initial velocity/time taken

5 0

2 years ago

What is a risk of using chemical pesticides on crops?

irakobra [83]

Answer:

a. chemical contamination of streams ans rivers

d. adaptation

4 0

2 years ago