Two students choose different reference levels while discussing the potential energy…
PHYSICS · Multi-part · CBSE · Physics · Work and Energy · Work and Energy
Problem
Two students choose different reference levels while discussing the potential energy of a book of mass 1.5kg kept on a shelf 2.0m above the classroom floor. Student X takes the floor as the reference level, whereas student Y chooses the top of a table that is 0.8m high as the reference level.
(i) Explain how the numerical value of gravitational potential energy of the book differs for the two students.
(ii) Calculate the potential energy of the book according to each student. Take g=9.8ms−2.
(iii) For each student, the book is gently pushed so that it falls from the shelf to the floor without friction. Compare the total mechanical energy (kinetic + potential) of the book (a) at the shelf and (b) just before touching the floor for both reference choices.
(iv) Based on your results, justify whether the choice of reference level affects the principle of conservation of mechanical energy.