SOLUTION: It has been estimated that 1000 curies of a radioactive substance introduced at a point on the surface of the open sea would spread over an area of 36000 km^2 in 40 days. Assuming

Question 127641This question is from textbook algebra and trigonometry with analiytic geometry
: It has been estimated that 1000 curies of a radioactive substance introduced at a point on the surface of the open sea would spread over an area of 36000 km^2 in 40 days. Assuming that the area covered by the radioactive substance is a linear function of (t) time and is always circular in shape, express the radius (r) of the contamination as a function of (t).
please i need your help, i don't know how... This question is from textbook algebra and trigonometry with analiytic geometry

Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
It has been estimated that 1000 curies of a radioactive substance introduced at a point on the surface of the open sea would spread over an area of 36000 km^2 in 40 days. Assuming that the area covered by the radioactive substance is a linear function of (t) time and is always circular in shape, express the radius (r) of the contamination as a function of (t).
:
Take the area of a circle equation; A = pi*r^2
:
we want to solve for r
:
pi*r^2 = A
:
r^2 =
:
r =
:
Find the radius (km) after 40 days using the given area of 36000
r = }
r =
r = 107 km
:
Find the slope using the coordinates of 0,0 (0 days, 0 radius) and 40, 107
m =
:
r = t; is the equation. (t (days) is on the x axis and the radius(km) is on the y axis):
if you graphed it would look like this:

Using your calibrated eyeball, you can see on the graph that after 40 days the radius is about 100 km
:
:
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