Why Does a 3D Body Turn Differently Based on Force Angle and Propulsion?

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Discussion Overview

The discussion revolves around the dynamics of a 3D body in motion, specifically how the angle of applied forces affects its turning behavior and path. Participants explore scenarios involving constant velocity, forces applied at angles, and the role of torque in determining the body's orientation and trajectory. The scope includes theoretical considerations and practical examples such as airplanes and satellites.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant describes a scenario where a force applied at an angle to a moving body should result in a curvilinear path, questioning why it behaves differently in various cases illustrated in an image.
  • Another participant asserts that a body cannot rotate without a net torque, suggesting that a linear force alone will change the path without altering orientation.
  • Discussion includes the distinction between linear forces and angular torques, with an example of vehicles like cars and planes that experience both when turning.
  • A participant raises questions about pendulum-like behavior in 3D objects and how centripetal forces influence orientation, comparing it to airplane banking and satellite motion.
  • Concerns are expressed about the conditions under which objects change orientation, particularly in the context of airplanes and the effects of lift and airflow.
  • One participant acknowledges the complexity of the scenarios, indicating that each case has specific conditions that affect the outcome.

Areas of Agreement / Disagreement

Participants express differing views on how forces and torques interact to influence the motion and orientation of 3D bodies. There is no consensus on the correct interpretation of the scenarios presented, and multiple competing views remain throughout the discussion.

Contextual Notes

Participants reference specific conditions and assumptions related to the forces and torques acting on the bodies, but these are not fully resolved. The discussion highlights the complexity of motion dynamics without reaching definitive conclusions.

Who May Find This Useful

This discussion may be of interest to those studying dynamics, physics of motion, or engineering principles related to vehicle and satellite behavior.

firavia
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I have created such a thread in the past but it was misinterpreted and I haven't been given the help I needed , this time I shall explain more about what is going wrong through a figure .
sorry for my bad english.

topic:
when a 3d body is going at constant velocity in a straight line and suddenly a force in its center of gravity was applied and has a certain angle with its initial velocity vecotr the body will make a turn and it will go in a curvilinear path if this force persist , my question why does that body when it turns it turns like in case "1" in the image below and not like in case 2 in the image:

[URL]http://www.mypicx.com/uploadimg/913064521_04142010_1.jpg[/URL]

and when does a body rotate like in case 2 ?

if the same body shown in the figure has a propeller engine that when is activated its force acts on its center of gravity and perpendicular to it s initial velocity will the body rotate the same way as in case 1 or it shall go sideways like in case 2 ?
please help telling me the difference .
 
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if the object moving in a straight line with constant velocity, and not rotating, is acted on by a force which acts at an angle to the initial path, applied thru its center of mass, then it must take a curvilinear path as shown in Option 2, not as shown in Option 1. It cannot rotate if there is no net torque applied to the object.
 
A linear force is required to change the objects path, an angular torque is required to change the objects orientation. In the case of a car or plane in a turn, then there is both a force and a torque involved.
 
Why in the case of a 3d object hinged with a cable that is attached at a center like a pendulum the centripetal force which is always perpendicular to the object center of gravity do orient the object and make it revolve like in case "1" , what is the difference ?

and in the case of an airplane if the plane bank it must go in a curvilinear path like in case "2" because of the horizental component of its lift force , but that's not what really happen because when a plane do bank it go in a curvilinear path and it change its orientation like in case "1"?
and in artificial satelites built by men when they orbit the Earth they do act like a pendulum where in this case the cable of the pendulum is attached to the center of the Earth so that the satellite will act like in case 1 in the figure above.!
if it is not the case in a plane what does make a plane change orientation while going in a curvilinear path other thn the horizental component of "lift" force ?

sorry again for my bad english.
 
firavia said:
Why in the case of a 3d object hinged with a cable that is attached at a center like a pendulum the centripetal force which is always perpendicular to the object center of gravity do orient the object and make it revolve like in case "1" , what is the difference ?
If the object had sufficient angular inertia, and if the attachment point was a low friction bearing then object would resemble case 2 for a while, but any friction at point of attachment would generate a torque that would eventually spin the object into a case 1 condistion.

In the case of an airplane if the plane bank it must go in a curvilinear path like in case "2" because of the horizental component of its lift force , but that's not what really happen because when a plane do bank it go in a curvilinear path and it change its orientation like in case "1"?
If the plane doesn't curve horizontally, then the air flow pushes against the side of the airplane and the vertically oriented stabilizer, and weather vane effect causes the plane to yaw into the direction it's headed.

artificial satelites
Satellites in orbit are virtually friction free and their rate of rotation is independent of their orbital path. Depending on the satellite, small thrusters may be used to keep it facing some far away object (Hubble telescope) or facing the Earth (some communications satellites).
 
I reaaly do thank you , cause U HAVE finnaly convinced me it seems every case has its conditions , thank you jeff : )
 

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