Weight Lifter and Barbell: A Fun Physics Adventure
How does the force exerted by a weight lifter on a barbell compare to the force exerted by the barbell on the weight lifter?
a. With the barbell at rest.
b. With the barbell moving upward.
c. With the barbell moving downward.
Answer:
According to Newton's third law of motion, for every action, there is an equal and opposite reaction. When a weight lifter lifts a heavy barbell above his head, the force he exerts on the barbell is equal and opposite to the force the barbell exerts on him. The force exerted by the weight lifter on the barbell is equal in magnitude but opposite in direction to the force exerted by the barbell on the weight lifter. Let's dive deeper into each scenario.
Detail Explanation:
When the barbell is at rest, there are no changes in momentum, and the momentum is conserved. Thus, the force exerted by the weight lifter on the barbell is equal and opposite to the force exerted by the barbell on the weight lifter, which means that the momentum of the system remains constant.
When the barbell is moving upwards, the weight lifter must exert more force than the barbell, causing his body to push down on the floor harder. This makes his muscles work harder and increases the force he applies to the barbell. The force exerted by the weight lifter on the barbell is greater than the force exerted by the barbell on the weight lifter, leading to an increase in momentum of the system.
When the barbell is moving downwards, the weight lifter's muscles will have to work hard to slow the barbell down and prevent it from hitting the ground. The force exerted by the weight lifter on the barbell is less than the force exerted by the barbell on the weight lifter, resulting in a decrease in momentum of the system.