A girl handles a suitcase in three different situations involving the same suitcase…
PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A girl handles a suitcase in three different situations involving the same suitcase of weight 150N.
Situation I: She lifts the suitcase vertically upward through 1m from the floor to a bench.
Situation II: She carries the suitcase horizontally at constant speed for 15m across the platform.
Situation III: She slowly lowers the suitcase vertically downward through 1m from the bench back to the floor while still holding it.
Answer the following questions.
(i) For each situation state whether the work done by the girl on the suitcase is positive, negative or zero.
(ii) Rank the magnitudes of work done by the girl in the three situations from greatest to least and justify your answer.
(iii) Giving reasons, comment on whether the physical effort felt by the girl necessarily matches the work done as obtained in part (ii).