Rotational Motion: Can 1 Force Make It?

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SUMMARY

A single force cannot produce pure rotational motion in a free body. If the force is applied through the center of mass, only linear motion occurs. However, when the force is applied off-center, it results in a combination of rotational and linear motion. To achieve rotation without linear motion, the force must be divided into a "couple" of equal and opposite forces around the center of mass, alongside a force through the center of mass for linear motion. This balance is crucial for maintaining momentum and energy during motion.

PREREQUISITES
  • Understanding of free body diagrams
  • Knowledge of center of mass concepts
  • Familiarity with rotational dynamics
  • Basic principles of force and motion
NEXT STEPS
  • Study the concept of "couples" in physics
  • Explore the principles of rotational dynamics in detail
  • Learn about the effects of off-center forces on motion
  • Investigate real-world applications of rotational motion in engineering
USEFUL FOR

Physics students, mechanical engineers, and anyone interested in the principles of motion and force dynamics.

nkehagias
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It is possible for a free body to make rotational motion with the effect of one only force?
 
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Not "pure" rotational motion. If the single force happens to be through the center of mass then you would get pure linear motion. If the single force is applied on a line not through the center of mass, then you will get a combination of rotation about the center of mass and linear motion. You would need to divide the force into a "couple"- a pair of equal but oppositely directed forces (so they add no linear motion) equally spaced about the center of mass to create the rotation- and a force through the center of mass to create the linear motion. You would need to set the forces so that the change in total momentum and energy is correct for the force applied.
 
An unbalanced free-body will tend to rotate or otherwise move towards its attractive force. But this is only temporary(until balance is achieved). Sustained peak cycling of this has never been demonstrated to my knowledge.
 

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