Motion under gravity and forces

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SUMMARY

The discussion focuses on the dynamics of a body falling under the influence of gravity and the application of opposing forces. When a downward force equal to the gravitational force (mg) is countered by an upward force of the same magnitude, the net force remains zero, resulting in no movement. To achieve a state of suspended motion, the applied force must equal mg, and to initiate upward movement, the applied force must exceed mg. The acceleration of the body is directly influenced by the magnitude of the applied force, determining the rate of change in velocity.

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  • Understanding of Newton's laws of motion
  • Familiarity with the concepts of force and acceleration
  • Knowledge of gravitational force (mg)
  • Basic principles of dynamics and kinematics
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  • Learn about the relationship between force, mass, and acceleration (Newton's Second Law)
  • Explore the concept of equilibrium in physics
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Physics students, educators, and anyone interested in understanding the principles of motion under gravity and the effects of applied forces on objects.

D. Wani
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If a body is falling downward under the effect of gravity(=mg) and someone applies a force(=mg) in the opposite direction (upward), then the body will continue moving downwards as the net force is zero. What would be the magnitude of the force applied such that the body would freeze in midair(if possible) and what would be the magnitude of the force applied such that the body would start moving upwards?
 
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Those are not fixed force values. Force determines acceleration, not speed. If the acceleration is upwards, the body will get slower over time, stop, and then start moving upwards. The timescale depends on the force. To keep it at rest, the force has to drop to mg once the object stops.
 
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