Alex and John are loading identical cabinets onto a truck. Alex lifts his cabinet straight up from the ground to the bed of the truck, whereas John slides his cabinet up a rough ramp to the truck. Which statement is correct about the work done on the cabinet-Earth system?

Question

Alex and John are loading identical cabinets onto a truck. Alex lifts his cabinet straight up from the ground to the bed of the truck, whereas John slides his cabinet up a rough ramp to the truck. Which statement is correct about the work done on the cabinet-Earth system? (A) Alex and John do the same amount of work. (B) Alex does more work than John. (C) John does more work than Alex. (D) None of those statements is necessarily true because the force of friction is unknown

Tardigrade Admin · Accepted Answer

Assuming that the cabinet has negligible speed during the operation, all of the work Alex does is used in increasing the gravitational potential energy of the cabinet-Earth system. However, in addition to increasing the gravitational potential energy of the cabinet- Earth system by the same amount as Alex did, John must do work overcoming the friction between the cabinet and ramp. This means that the total work done by John is greater than that done by Alex.

Q. Alex and John are loading identical cabinets onto a truck. Alex lifts his cabinet straight up from the ground to the bed of the truck, whereas John slides his cabinet up a rough ramp to the truck. Which statement is correct about the work done on the cabinet-Earth system?

Alex and John do the same amount of work.

Alex does more work than John.

John does more work than Alex.

None of those statements is necessarily true because the force of friction is unknown