A weight lifter struggles but manages to keep a heavy barbell above his head.

A weight lifter struggles but manages to keep a heavy barbell above his head. Occasionally he slips and the barbell starts to fall downward but he always recovers. Compare the force exerted by the weight lifter on the barbell to that of exerted by the barbell on the weight lifter. Is one force larger then the other or are they in equal magnitude to one another. Does this change during the times when the barbell slips downward? Explain.

these are what are called reaction forces. the force the man is exerting on the barbell is always equal to what the barbell is exerting on him. it can be misleading as the barbell is moving downwards, but this just means the reaction pair of gravity on the barbell and visa versa is larger than the reaction pair of the man on the barbell and the barbell on the man. it can be difficult to get your head around.
when the barbell slips the forces exerted on the barbell by the man and visa versa are still equal to each other, but they have both decreased. hope i helped x

Leave a Comment