A weight lifter struggles but manages to keep a heavy barbell abovehis head. Occ

Question

A weight lifter struggles but manages to keep a heavy barbell abovehis head. Occasionally he slips and the barbell starts to falldownward, but he always recovers. Compare the force exerted by theweight lifter on the barbell to that exerted by the barbell on theweight lifter. Is one force larger than the other or are they equalin magnitude? Does this change during the times when the barbellslips downward?

Same with a bowling ball rolls down the alley and hits a pin andtennis player hits the ball with her racket. Does the relationshipof the magnitudes of the two forces change at any time during thecollision?

Explanation / Answer

actually in the weight lifter case internal force exerted by bodieson each other are always of same magnitude....but the thingthat matters is that there magnitude can change depending upon thesituation...consider when the barbell slips and start comingdownward internal forces acting in between weight lifter andbarbell is less then force exerted by gravity on barbell., as a result it start coming down. now as weight lifter starting resisting it...the in between themincreases...till it becomes equal .....so forces in between themalways remains same but its magnitude depends upon motion during collision forces acting in between them increases till thebodies become relatively at rest(bodies compress initially ....thenequillibrium state at which there is maximum force.....after thatbodies start expanding or foce decrease) i thought everything is clear to you...or u can ask forclarification...but i guess its better if u think why is newtonsthird law valid.....what makes newton write that law...try to getthe logic...everything wud be crystal clear then...

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