Answer:
The rate of change of the shadow length of a person is 2.692 ft/s
Solution:
As per the question:
Height of a person, H = 20 ft
Height of a person, h = 7 ft
Rate = 5 ft/s
Now,
From Fig.1:
b = person's distance from the lamp post
a = shadow length
Also, from the similarity of the triangles, we can write:

Differentiating the above eqn w.r.t t:
Now, we know that:
Rate = 
Thus
Answer:
oxygen is used up is the answer
Explanation:
These vaporized molecules are drawn up into the flame, where they react with oxygen from the air to create heat, light, water vapor (H2O) and carbon dioxide (CO2).
<span>When a magnet moves near a wire, it's changing field causes the electrons in the wire to flow as electric current.</span>