Monday, October 28, 2013

How many pencils do you think it would take to cover the sun?

1.  Background Story:  
How many pencils do you think it would take to cover the sun?    A million, 2 million, a billion? I chose this question because it seemed like it would be interesting and challenging to figure out. I  do not think there is anyway to estimate the answer; that is why I think it will be so interesting. 

2.  Ask Yourself This:  

1. What is the surface area of the sun in square miles?
2. What is the surface area of a standard, unsharpened, # 2 pencil?
3. How many pencils does it take to cover a square foot?
4. How many square feet are in a square mile? 

3.  Helpful Hints:  

          A. 1. According to the NASA website, the surface of the sun is 2,347,017,636,988     square miles. Another way to list it is 6.07877x10 ^2 sq kilometers. 
          2. I measured the width of a pencil to be .7 centimeters.
          3. I measured the length of a pencil to be 18.7 centimeters.
          4. 2.788x10^7 square feet are in a square mile.  (Source: Google unit converter) 
          5.1 sq. foot = 929 cm. sq.  (Source: Google unit converter) 

B.   I measured a standard pencil with a metric ruler.  Then I  multiplied  the width  (.7 cm)  by the length (18.7cm) to get the surface area of a pencil. 


4.  Construct a Formula: 

pencils     X   feet sq.  X   miles sq.    =  pencils                                                                         feet sq.          miles sq.       sun.                sun 



5.  Messy Math: 

I measured a standard pencil with a metric ruler.  I  will  multiply the width  (.7 cm)  by the length (18.7cm) to get the surface area of a pencil. 

surface area of a pencil is .7cm. x 19 cm. = 13.3cm sq.
1 sq. foot = 929 cm. sq.
929 cm. sq. / 13.3 = 70 pencils in 1 sq. foot
27,878,400 sq ft per square mile

70 pencils x 27,878,400 sq ft. = 1.95x10^9 pencils per square mile 

1.95x10^9 pencils per square mile  X 2.35x10^10 surface area of sun=  4.6x10^19pencils to cover the sun

6.  Answer: 

It would take 4.6x10^19 pencils to cover the sun. (that’s a TON of pencils!!!!!!!)
ps not the weight the expression  


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