Question

A. State whether work is said to be done in each case. Give reasons to justify your answer. 1. Reading a story book 2. Opening the lid of a tin 3. Standing under a tree 4. Cutting a piece of​

Answer 1

Answer:

friend  i have two answers for that :

Explanation:

firstly work in normal definition means : mental or physical effort , and that's why in each case you can say the work is done .

                                                         BUT

work definition in science  means  when a force applied to an object moves an object ,and in the above cases only the second case is acceptable to this definition .

hope it helps !!

Answer 2

Answer:

Work is done in cases  2 and 4 whereas in case 1 and  3 work is not done

Explanation:

Case-1) -Work is done whenever a force or a component of a force results in a displacement. No component of the force is acting in the direction of motion when the book is moved horizontally with a constant velocity. The force and the displacement are independent. No work is done by the hand on the book.

Case-2)When we open a lid displacement of the lid takes place so work is done

Case-3)No displacement of the persons body or the tree so work is not done

Case-4)While cutting something we  use a knife which gets displaced so work is done

thanks

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