Question

A man lifts a 10 kg sack of rice from a ground to above his head using his both hands. The sack of
rice does not experience a change in kinetic energy between the two positions. Which of the
following statement is correct?
A The work done on rice sack by gravity is less than the work done on rice sack by man.
B The work done on rice sack by gravity is more than the work done on rice sack by man
C The work done on rice sack by gravity is equal to the work done on rice sack by man.
D There is no work done on the rice sack

Answer 1

can u please clarifie this doubt for me

Answer 2

the work done by gravity = - m g h (F down, motion direction x up)
the work done by the man = + m g h (F up, motion direction x up)