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The question is to explain why it is considered work done or not

Explain the following observation
Mary's mother, who is pushing a grocery trolley, is considered to be doing work.
Mary, who is carry a 10kg packet of rice while walking, is not considered to be doing any work on the rice

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J.R. S. | Ph.D. in Biochemistry--University Professor--Chemistry TutorPh.D. in Biochemistry--University Profes...
4.9 4.9 (38 lesson ratings) (38)
Work is defined as force x distance.  But it should be noted that the distance has to be in the same direction as the force being applied.  So, while Mary's mother is doing work because she is pushing the cart and is applying force in the same direction as she is pushing, Mary is not applying a force in the direction that she is moving the packet of rice.  She is applying a small force to lift the packet but the direction opposite that of gravity (vertical), while the direction of movement is horizontal.  Maybe a physics tutor will provide a better answers, but this is the simplified explanation.