iscusses problems with her friends, and pebble moves performs experiments. She expends a lotof a force on the pebble and the displaced. In this situation parlance, She is 'working hard'. All this 'hard A girl pulls a trolley and the tre shall study these concepts. Work' may involve very hittle 'work' if ge goby the frolley and it is have to perform several basie activities to the scientific definition of work. survive. We call such activities 'life processes'. Let us say the rock does not move despite all Lift a book through a height The energy for these processes comes from I the effort. You get completely exhausted. You must apply a force. The bo food. We need energy for other activities like However, you have not done any work on the There is a force applied on the playing. singing. reading, writing, thinking. rock as there is no displacement of the rock. book has moved. Hence, work jumping. cycling and running. Activities