Explanation wanted for a demonstration in MIT phyiscs lec #6

sganesh88

We can't say that. You're missing the other forces in the picture. If a body is subjected to a constant net force of F newton for t seconds, its change in momentum will be, magnitude of F multiplied by t, yes. Here the 50 N isn't the net force.

Force isn't a substance to be transferred. It is applied.
And regarding the situation you mentioned where the string breaks, if the string had indeed maintained a constant force of 50 N for the time 0.5 s on the body under the influence of no other forces before breaking, then yes. the body should have a change in momentum of 25 Kgm/s.

cfung

I may have used the wrong diction, pardon me for that, but in that context I meant force as being "propagated".

Though thank you for your clarification on the subject of impulse.