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

Weight before/after change in rotation Speed

  • Thread starter Charanjit
  • Start date
  • #1
48
0

Homework Statement



How would the weight of a person in some place (48 North and 123 West) change if the rotation rate increased so a day was 3 hours long?


Homework Equations



F=ma

The Attempt at a Solution



The above is not the only equation I think that is needed for this. Not sure about this, but coriolis force maybe needed. I just have no clue about this.
 

Answers and Replies

  • #2
rude man
Homework Helper
Insights Author
Gold Member
7,627
714
Sum of forces on the person = 0 since he's not going anywhere (hint: there are 3 terms in the equation, and yes, it's basically F = ma, except if you're going to derive evbrything you need from that one equation, remember that F and a are vectors, not just scalars).
 
  • #3
48
0
Yes, I understand that F=ma = 0 since the person will not move. Now the three terms that come into play... would the centrifugal force help at all since the earth is rotating?
 
  • #4
rude man
Homework Helper
Insights Author
Gold Member
7,627
714
Yes it would. Since gravitational attrcation is constant, irrespective of rotational speed, what force do you think has to change so the three add up to zero?
 
  • #5
263
0
You are working in a frame fixed to the earth which is a rotating object hence you are in a rotating frame. Which means that you need to use fictious forces. You need the centrifugal force. The coriolis force is tangent to the earths surface... Calculate the component of the centrifugal force normal to the surface of the earth...
 

Related Threads for: Weight before/after change in rotation Speed

Replies
1
Views
657
Replies
1
Views
2K
Replies
2
Views
3K
  • Last Post
Replies
2
Views
2K
Replies
1
Views
3K
Replies
24
Views
2K
  • Last Post
Replies
1
Views
616
Replies
3
Views
3K
Top