A student carries a 4.0 kg backpack by its handle while walking 12 m along a straight…
PHYSICS · Multi-part · CBSE · Physics · Work and Energy · Work and Energy
Problem
A student carries a 4.0 kg backpack by its handle while walking 12 m along a straight horizontal hallway at constant speed. The backpack is held at a constant height 0.80 m above the floor, and its position relative to the student does not change during the walk.
(1) Describe the displacement of the backpack relative to Earth during the walk, specifying both magnitude and direction.
(2) State whether the work done on the backpack by the gravitational force during the walk is positive, negative, or zero, and explain your reasoning without using equations.
(3) The student’s hand exerts an upward force on the backpack. Indicate whether this force does positive, negative, or zero work on the backpack, and justify your answer qualitatively.
(4) Considering your previous answers, explain how the backpack’s kinetic and potential energies change, if at all, during the walk and reconcile these changes with the total work done on the backpack.