Physics Of Walking || Friction

[三民東大物理]

Some NOTES and paraphrase：
If a human body is considered as an extended object(a multiple particles system), change of its kinetic energy during walking is equal to the work from internal force plus the work from the surrounding. Work can be seen as the applied force accumulated in space, therefore it is the internal work provides the kinetic wnergy when walking. On the other hand, momentum can be seen as the applied force accumulated in time. Though no displacements on the friction force at all, it can still provide the human momentum when walking.

[sakumieika]

I don't understand, how can it affect momentum without affecting acceleration nor KE? isn't it the same meaning?

[lakshyasingh]

Point of contact displaced our leg displaced.... How is work done 0

[arunbhardwaj]

AT FIRST U ARE SAYING INCREASES OUR MOMENTUM WHILE WALKING, , , AND AT LAST U ARE SAYING THAT, , IT DOES NOT PROVIDE US ACCELERATION, , , HOW CN BOTH STATEMENT BE TRUE??IF FRICTION IS CHANGING OUR MOMENTUM IT CLEARLY MEANS THAT, ,IT IS PROVIDING US SOME ACCELERATION

[grishmgarv]

brilliant conceptual risk taken which nobody can explain, ,amazing explaination

[prabhudevmhiremath]

Nice explanation. What is force generated by a kid while walking who has 20 kgs of weight?

[SauravKumar-gxsc]

this is a contradiction, kinetic energy comes from muscular force and momentum by friction force ? I think you are not cleared .Sorry but its true .

[hkiyr]

bro my brain hurted watching this video, but in a good way