• Support PF! Buy your school textbooks, materials and every day products Here!

Order of magnitude problems

  • #1
1. If the entire population of the United States forms a human chain by holding hands, how many times can such a chain be wrapped around the earth's equator. Round your answer to the nearest integer.



2. There were no formulas given for this problem. I googled the length of the earth's equator: it is 6.37 *10^6m and I know that the United States has about 300 million people



3.I tried multiplying 300 million with 6.37*10^6 and got the answer wrong. I'm completely desperate now; I don't have enough information to solve this problem
 

Answers and Replies

  • #2
tony873004
Science Advisor
Gold Member
1,751
142
The length of Earth's equator is not 6.37*10^6. That is its radius. You need to multiply this by 2pi to get the circumferance.

You might be able to space your people a little farther than 1 meter apart.
 
  • #3
mgb_phys
Science Advisor
Homework Helper
7,774
12
The point of this kind of problem isn't to google the data - it is to be able to find a way of estimating the values you need, at least to within a factor of a few.

So the circumference of the earth. The metre was originally defined as 10,000,000 the distance form the equator to the North Pole, so the eath's circumference is about 40,000Km. If you didn't know this - what's the distance between say New York and LA, howmany time zones apart are they. Since there are obviously 24 timezones around the earth you can get the circumference.
 
  • #4
Vanadium 50
Staff Emeritus
Science Advisor
Education Advisor
2019 Award
24,540
7,423
I tried multiplying 300 million with 6.37*10^6
Why did you decide multiplying was the thing to do?
 

Related Threads on Order of magnitude problems

  • Last Post
Replies
1
Views
7K
Replies
10
Views
623
Replies
1
Views
5K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
2
Views
7K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
5
Views
8K
  • Last Post
Replies
6
Views
737
Replies
2
Views
896
Top