The concept of a force lifting a weight and the work done

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When applying a constant force of 100N to lift a 2kg mass over a distance of 3m, the work done is calculated as W = F × d, resulting in 300J. The discussion highlights confusion regarding the work done by gravity, which is not zero, as it opposes the lifting force. The conversation emphasizes the importance of clearly defining work and energy transfer, particularly in systems with friction. It is noted that while friction can do negative work, it complicates the understanding of energy dissipation. Ultimately, the key takeaway is that work is defined by the force applied over a distance, regardless of other forces acting on the system.
  • #31
Mister T said:
Note that if one insists that the friction force does work,
You just apply the definition of work to both bodies (A, B) and the two equal but opposite friction forces acting on them.

Mister T said:
it is not possible to explain where the energy is going.
For kinetic friction the work done by A on B is of different magnitude than the work done by B on A. That difference represents the energy dissipated as heat.
 
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