Weight of an Astronaut Between Two Stars - Newton's Laws of Motion Explained

  • Thread starter Thread starter trulyfalse
  • Start date Start date
  • Tags Tags
    Dynamics Theory
Click For Summary
An astronaut positioned at the midpoint between two equal-mass stars experiences weightlessness due to the equal gravitational forces acting in opposite directions, effectively canceling each other out. While the astronaut is indeed weightless, this state is not solely due to the gravitational balance; it also relates to the concept of free fall. In orbit around a single star, an astronaut would also feel weightless because they are in a continuous state of free fall towards the star, despite the presence of gravitational force. The discussion emphasizes that weight is defined by the force exerted on an object, which can be influenced by the surrounding gravitational environment. Understanding these principles is crucial for grasping the nuances of Newton's laws of motion in space.
trulyfalse
Messages
35
Reaction score
0
I'm back again, this time regarding questions relating to Newton's laws of motion. :)

Homework Statement


Imagine an astronaut in space at the midpoint between two stars of equal mass. If all other objects are infinitely far away, how much does the astronaut weigh? Explain your answer.

The Attempt at a Solution


I'm not sure how to answer this, my initial thought was weightless, because equal forces of gravity are acting in opposite directions.
 
Physics news on Phys.org
He would be weightless, yes, but not for the reason you mention.

If you think about weight of an object as how much force is applied to the surface of this object (i.e. how much force an astronaut feels on his feet when standing), then under what circumstances would there always be weightlessness? Would an astronaut in orbit around a single star be weightless despite that he is accelerated by gravity?
 
Last edited:

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?
View full post »

Similar threads

Proving Newton's 3rd law from conservation of momentum
  • · Replies 2 ·
Replies
2
Views
836
Solving for Acceleration when weight is in Newtons instead of Kg
  • · Replies 6 ·
Replies
6
Views
2K
Rank forces according to magnitude: Newton's 2nd/3rd laws
  • · Replies 5 ·
Replies
5
Views
7K
Newton's Third Law Problem: Two masses, a rope and a pulley
  • · Replies 21 ·
Replies
21
Views
10K
Undergrad Newton's Third Law: Action & Reaction Along the Line Connecting Two Objects
  • · Replies 5 ·
Replies
5
Views
2K
Relationship between material mass and weight
  • · Replies 5 ·
Replies
5
Views
2K
Newton's third law a book and table
  • · Replies 2 ·
Replies
2
Views
14K
Can anyone explain more for me Newton's 3rd Law of Motion?
  • · Replies 3 ·
Replies
3
Views
4K
Two Questions on Newton Law Problems
  • · Replies 5 ·
Replies
5
Views
2K
Circular motion in the vertical plane
  • · Replies 1 ·
Replies
1
Views
2K