Force of Gravity


by thelightsare
Tags: gravitaional force, newtons law
thelightsare
thelightsare is offline
#1
Dec31-10, 04:18 PM
P: 9
1. The problem statement, all variables and given/known data
In this problem find the force of gravity of Al. Al is standing at the top of Mt. Everest at an elevation of 8,848 m. Al has a mass of 58 kg. The earth has a mass of 5.97e24 and a radius of 6.38e6m. What is the force of gravity acting on Al?


2. Relevant equations

F = GMm/r^2

3. The attempt at a solution
the dist. used to find F is from Al to the Earth's center ?
so r = 8848+6.38e6 ??????
then plug in values

F = G 58(5.97e24)/(8848+6.38e6)^2
F[tex]\approx[/tex]569.385 N?

Is this right? I feel like i'm missing soemthing
Phys.Org News Partner Science news on Phys.org
Cougars' diverse diet helped them survive the Pleistocene mass extinction
Cyber risks can cause disruption on scale of 2008 crisis, study says
Mantis shrimp stronger than airplanes
PhanthomJay
PhanthomJay is offline
#2
Dec31-10, 04:54 PM
Sci Advisor
HW Helper
PF Gold
PhanthomJay's Avatar
P: 5,966
Quote Quote by thelightsare View Post
1. The problem statement, all variables and given/known data
In this problem find the force of gravity of Al. Al is standing at the top of Mt. Everest at an elevation of 8,848 m. Al has a mass of 58 kg. The earth has a mass of 5.97e24 and a radius of 6.38e6m. What is the force of gravity acting on Al?


2. Relevant equations

F = GMm/r^2

3. The attempt at a solution
the dist. used to find F is from Al to the Earth's center ?
so r = 8848+6.38e6 ??????
then plug in values

F = G 58(5.97e24)/(8848+6.38e6)^2
F[tex]\approx[/tex]569.385 N?

Is this right? I feel like i'm missing soemthing
Hi, welcome to PF! Your equation is correct, but perhaps the values you are using are a bit off, since Al would weigh about 569 N at sea level, (more or less, depending on variabilities in earth's radius, etc), then he should weigh a wee bit less atop the Mount. But in terms of significant figures, essentially, he weighs pretty much about the same on top as he does at the bottom.
thelightsare
thelightsare is offline
#3
Dec31-10, 05:01 PM
P: 9
Hi! Thanks you for the welcome and your help. And just for reassurance, for r was i right to add the two values together?

PhanthomJay
PhanthomJay is offline
#4
Dec31-10, 06:32 PM
Sci Advisor
HW Helper
PF Gold
PhanthomJay's Avatar
P: 5,966

Force of Gravity


Quote Quote by thelightsare View Post
Hi! Thanks you for the welcome and your help. And just for reassurance, for r was i right to add the two values together?
Yes, the distance apart is measured to Earth's center.
thelightsare
thelightsare is offline
#5
Dec31-10, 10:34 PM
P: 9
Thanks so much!


Register to reply

Related Discussions
The speed of light, gravity, strong force, weak force Quantum Physics 9
The Difference between Acceleration Due to Gravity and the Force Due to Gravity? Introductory Physics Homework 2
How do i calculate a normal force when gravity is not the only force involved?? Classical Physics 4
Using electric force to find the force of gravity Introductory Physics Homework 3
Question: Electromagnetism, Weak-force, Gravity, Strong Nuclear force ? General Physics 11