Throwing a ball horizontally on the moon and pushing it in the spacestation

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Discussion Overview

The discussion revolves around the differences in force required to throw a ball horizontally on the Moon compared to pushing it horizontally in a space station. Participants explore the implications of gravity, atmospheric conditions, and the mechanics of motion in different environments.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants note that the mass and inertia of the ball remain constant regardless of location, suggesting that the force required to change its speed is the same in both environments.
  • Others point out that the presence of atmospheric drag in the space station contrasts with the negligible drag on the Moon, which may influence the force needed to achieve horizontal motion.
  • A participant questions the initial premise by asking for clarification on what specific difference in force is being referred to.
  • Another participant emphasizes that any amount of force can initiate horizontal motion, and the distance traveled depends on the duration of the force application rather than the force itself.
  • One reply suggests that if the ball is to travel parallel to the surface, the force required would depend on whether the object is already in motion (as in a circular orbit) or stationary on the Moon's surface.
  • Another participant discusses the relationship between horizontal and vertical forces, indicating that while horizontal force may remain constant, vertical acceleration is influenced by gravity, which could affect the overall dynamics of the motion.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the forces involved and the conditions affecting motion, indicating that there is no consensus on the specifics of the force required in each scenario.

Contextual Notes

Participants highlight the importance of clarifying assumptions, such as the effects of gravity and atmospheric conditions, and the role of friction and air pressure in determining the forces involved.

Martyn Arthur
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Why is there a difference in force required throwing a ball horizontally on the moon and pushing it horizontally it in the spacestation
Thanks
 
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The mass and inertia of the ball is the same at both locations so no force difference there; however, there is an atmosphere maintained in the space station and therefore an aerodynamic drag resistance, whereas there is very little atmosphere on he moon so there is essentially no aerodynamic drag resistance there.
 
Martyn Arthur said:
Why is there a difference in force required throwing a ball horizontally on the moon and pushing it horizontally it in the spacestation
Thanks
The first question would be: What difference are you referring to?
 
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Thank you; I will try to be more clear, taking gravity away from all.
On the moon the astronaut requires the same force to throw the ball horizontally in the space station as the astronaut would on Earth.
On the space station would it require the same force to move a ball one meter, as it would to move the same ball horizontally one meter on Earth/ the Moon in the absence of friction and air pressure?

Thanks for your patience!
Martyn Arthur
 
Martyn Arthur said:
On the space station would it require the same force to move a ball one meter, as it would to move the same ball horizontally one meter on Earth/ the Moon in the absence of friction and air pressure?
Force doesn't move things, it changes their speed. The relevant equation is Newton's second law ##F=ma##; ##m## is the same in both cases so the same force will change the speed (##a## is the acceleration and that's just another word for "change of speed") by the same amount. And once you've started it moving, in the absence of friction and air resistance it will keep moving, so no matter how small a force you apply for how short of a time if you wait long enough it will have moved one meter.
 
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Could it be that the OP is talking about launching the same object so that it travels parallel with the surface of the Moon / Earth? It strikes me that the object would already be traveling horizontally in the space station if it's in a circular orbit so no force would be needed. If it's on the Moon's surface then you would need to accelerate it until it is in, effectively, a circular orbit at zero height above the surface. The Force needed would depend on how long or over what distance it acted so more information would be needed.
 
Martyn Arthur said:
Thank you; I will try to be more clear, taking gravity away from all.
On the moon the astronaut requires the same force to throw the ball horizontally in the space station as the astronaut would on Earth.
Any amount of force in the horizontal direction will "throw the ball horizontally". So this is a misleading statement.
On the space station would it require the same force to move a ball one meter, as it would to move the same ball horizontally one meter on Earth/ the Moon in the absence of friction and air pressure?
Any amount of force would start a ball moving in the horizontal direction. How far it will move is just a matter of how long you let it move. So this question can not be answered.
 
Only thing I see is if you are trying to get the ball to go 1 m before it hits the ground, you need to consider where it hits the ground. The horizontal force required to get the ball of fixed mass up to fixed horizontal velocity is essentially constant (ignoring air resistance), but the vertical acceleration is set by gravity. For a frictionless, elastic ball, the horizontal velocity doesn't change on impact with the ground (assuming a flat surface), so (it seems to me), the force required in all cases is constant if you care only about how fast the ball goes horizontally. If the ball needs to get over a mark on the ground 1m away, the required force (terminal horizontal velocity) on the ball increases with gravity.
 

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