How Does the Work-Kinetic Energy Theorem Apply When Raising a Ball Vertically?

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When raising a ball vertically at a constant speed, the work-kinetic energy theorem indicates that no net work is done on the ball due to its constant speed. However, as the ball is elevated, its potential energy increases, leading to a question about the conservation of total energy. The discussion highlights that the work-kinetic energy theorem is not universally applicable and is only valid under specific conditions. It clarifies that the work done on the ball equals the change in its mechanical energy, represented by the equation W = ΔK + ΔU. This emphasizes the need to consider both kinetic and potential energy changes when analyzing the system.
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Assume a situation that there is a ball on the ground. A vertical force is applied to raise the ball to h at a constant speed. According to work-kinetic energy theorem, no net work is done on the ball owing to the constant speed. However, the potential energy increases as the ball gains elevation. The total energy does not seem conservative in this case. Why?
 
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Welcome to PF;
The work-KE theorem you have been taught is wrong in general and can only be used in specific circumstances.
More completely, the work done on an object is equal to the change in it's mechanical energy. In this case: ##W=\Delta K + \Delta U##
 

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