A Comparison of Forces Between a Weight Lifter and a Barbell

Explanation:

(A) When the barbell is at rest, both forces will be equal and opposite in direction. This is because the force exerted by the weight lifter on the barbell is equal to the force exerted by the barbell on the weight lifter. Whereas, when the barbell is moved upward by the weight lifter, the force exerted on the barbell by the weight lifter will be greater than the gravitational force exerted on the weight lifter by the barbell and thus the direction is upward.

(B) When the barbell slips downward by the weight lifter, then we can say that the force due to gravity exerted by the barbell on the weight lifter is greater than the force exerted by the weight lifter on the barbell.