My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum

Thanks Tree1Thanks
  • 1 Post By skipjack
LinkBack Thread Tools Display Modes
June 4th, 2018, 09:27 AM   #1
Joined: May 2018
From: United States

Posts: 5
Thanks: 0

Math Focus: Algebra
Variation Linear Equation Problem

Problem: "The weight of an object varies inversely as the square of the distance from the center of the earth. At sea level (6400 km from the center of the earth), an astronaut weighs 100 lb. How far above the earth must the astronaut be in order to weigh 64 lb?"

I generally understand elementary Variation Linear Equations, but something about this question seems to be fundamentally throwing me off. Assuming that I understand the question correctly, I can successfully get the constant (4,096,000,000) , but something after that seems to have gone frightfully wrong as I consistently get an answer/distance of 80,000, which my book says is wrong.


(Now I find the square root of both sides to remove d's exponent)

Can anyone please tell me where I have gone wrong?
Ebba Sen Pai is offline  
June 5th, 2018, 06:43 AM   #2
Global Moderator
Joined: Dec 2006

Posts: 19,291
Thanks: 1683

The square root of 64,000,000 is 8000, not 80,000. Subtract 6400 km from 8000 km to get the distance above the earth's surface.
Thanks from Ebba Sen Pai
skipjack is offline  

  My Math Forum > High School Math Forum > Algebra

equation, linear, problem, variation

Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
Linear Equation Problem willreyes93 Linear Algebra 2 September 18th, 2014 01:07 PM
2nd order differential equation - variation of parameters Akcope Calculus 0 May 8th, 2014 11:26 AM
Linear Variation Proportion Xeon8 Algebra 4 April 27th, 2013 06:18 PM
Linear equation problem lumen8r Linear Algebra 1 March 9th, 2010 03:06 PM
Linear equation word problem okcomputer76 Linear Algebra 0 December 31st, 1969 04:00 PM

Copyright © 2018 My Math Forum. All rights reserved.