A crane lifts a 1000-kg steel beam off the ground, and sets it down on scaffolding 100 meters off the ground. All of the following are true EXCEPT:
A. The net work done on the steel beam is 9.8 × 10^5 J.
B. The net work done on the steel beam is 0 J.
C. The magnitude of the work done on the steel beam by gravity is 9.8 × 10^5 J.
D. The magnitude of the work done on the steel beam by the crane is 9.8 × 10^5 J.
Answer: A.
Well this is disappointing. I thought I knew my work and energy well. Please, no test taking strat suggestions. I know I can eliminate C and D. I'm looking for a conceptual understanding.
Why is net work done on the steel beam 0 J? In lifting it, its potential energy increases. Is this not work done?
thanks.
A. The net work done on the steel beam is 9.8 × 10^5 J.
B. The net work done on the steel beam is 0 J.
C. The magnitude of the work done on the steel beam by gravity is 9.8 × 10^5 J.
D. The magnitude of the work done on the steel beam by the crane is 9.8 × 10^5 J.
Answer: A.
Well this is disappointing. I thought I knew my work and energy well. Please, no test taking strat suggestions. I know I can eliminate C and D. I'm looking for a conceptual understanding.
Why is net work done on the steel beam 0 J? In lifting it, its potential energy increases. Is this not work done?
thanks.