Answer:
(a)
(b) 
Explanation:
Part (a)
The total length of copper cord L=86.3 m
The cross sectional area A=1.71×10⁻⁶m²
The resistivity of copper p=1.72×10⁻⁸Ω
Thus the resistance of extension cord is

Part (b)
The resistance of trimmer Rt=17.9 ohms
When voltage of 120V is applied then the current I is passing through series circuit is

Thus the voltage across the trimmer is:

Conservation tillage practices help reduce soil erosion and maintain soil nutrient levels.
<u>Explanation:</u>
The approach that helps in the reduction of doing tillage practices and also reducing its frequency. this is done for obtaining certain benefits for both environment and economic. This mainly focuses on providing sustainability by leaving some plants remaining in the soil.
It aims in decreasing the emission of gases of greenhouse effects like carbon dioxide. Using these practices helps in reducing the erosion and runoffs. This will promote health of the soil because the nutrients are not take off form the soil due to soil erosion and runoffs.
The answers to the respiratory questions are listed below:
- 6). Trachea
- 7). Pneumonia
- 8). True
- 9). False
- 10). Hair
<h3>Meaning of a respiratory system</h3>
A respiratory system is a biological system found in both plants and animals, which includes organs and structures used for exchanging gas between the organisms and its environments.
A respiratory system is a network or chain or organs and tissues that enables breathing.
In conclusion, the respiratory system is one that is very important to understand.
Learn more about respiratory system : brainly.com/question/1270124
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<span>Average velocity can be calculated by determining the total displacement divided by the total time of travel. The average velocity of an object does not tell us anything about what happens to it between the starting point and ending point. Average velocity is different from average speed because it considers the direction of travel and the overall change in position.</span>
<h2>Answer: free electrons</h2>
<u>Plasma</u> is known as the 4th state of matter and is itself ionized gas. In this sense, ionization consists of the production of ions, which are <u>electrically charged atoms or molecules due to</u><u> the excess or lack of electrons</u><u> with respect to a neutral atom or molecule.
</u>
That is why in this process there are always<u> free electrons</u>. Therefore in heating gas to create plasma can yield free electrons, and the correct option is D.