21.6 Worked Example: Block Going Down a Ramp

[@shubhamtiwari2435]

Prof. Lewin's Lecture are best for rich intutive grasping of the Subject. Prof. Dourmashkin's lectures are best for learning the decoding of physical phenomemon into mathematical equations. Best ! Rich ! and perfect for problem solving. Much needed lectures . Thanks MIT OCW , Thanks Prof. Deepto Chakrabarty, Prof. Prof. Anna Frebel and the team.. Thank you very much Prof Peter Dourmashkin :)

[@josuemanuelparejacontreras3443]

how he always end up in the right position at the end of each video??? hahahaha, no marker trace cover his face !!!

[@BTWPhysics]

The Work-Energy Theorem is incorrect to begin with and W ≠ Δk. Work is not a function of displacement and W ≠ F ⋅ ds. Kinetic energy is not 1/2mv^2 neither.

[@jackdawkins629]

I think we're still dealing with constant forces here so simplifications can be made

[@BTWPhysics]

@@jackdawkins629 It doesn't matter because the equation for the work-energy theorem is incorrect and ,so, W ≠ ΔK.

[@jackdawkins629]

@@BTWPhysics can you explain why it's wrong? is it the shortcut calculus you don't like or?

[@BTWPhysics]

​@@jackdawkins629 It's not the calculus that's wrong and ,thus, the calculus is fine. The work-energy concept that's being taught is incorrect. The energy transferred by an external force is not the work done by the force which also means that the change in kinetic energy does not reflect the net work done by the net force. If you push on an object such as ,for example, a wall or a chair, then there is an external force on the object. But, what are you actually doing or what is happening? You are transferring energy to the object in a specific direction. A greater external force on an object then would transfer a greater amount of energy to the object. This suggests or implies that there's a relationship between the amount of external force on an object and the amount of energy transferred to the object as opposed to a relationship between the work done on an object and energy transferred. The amount of energy transferred to an object by an external force would simply reflect the magnitude of the external force.

[@kvisachaderah896]

​@@BTWPhysicswhat are you talking about?? If you push a wall with a force, and the wall is not moving, then no energy is being transferred to the wall.