A weightlifter and a barbell are both at rest on a large scale. The weightlifter
ID: 1373381 • Letter: A
Question
A weightlifter and a barbell are both at rest on a large scale. The weightlifter begins to lift the barbell, ultimately holding it motionless above her head. Does the scale reading ever differ from the combined weight of the two bodies at any time during the lift? A weightlifter and a barbell are both at rest on a large scale. The weightlifter begins to lift the barbell, ultimately holding it motionless above her head. Does the scale reading ever differ from the combined weight of the two bodies at any time during the lift?Explanation / Answer
The scale reading will be different for situations when weightlifter lifts the barbell up, holding up without any acceleration upward and moving down the barebell.
At the beginning the lifter pushes the the barbell upward and barbell pushes the lifter downward by newton's third law. So the scale reads lifter's weight + barbell's weight + downward force by lifter while lifting. Therefore more than combined weight.
At the top over the lifter's head his acceleration on the barbell is zero. Now the scale reads only combined weight i.e lifter's weight + barbell's weight
As the lifter begins to brought it down the acceleration on barbell by lifter is reduced so the scale reading shows reduced weight i.e less weight of lifter + weight of barbell.
If the lifter is lifting the barbell with constant velocity then the scale will read equal weight for all situtation.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.