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If a book that weighs 7 N is picked up off the floor and put on a shelf 2 m high, the work done on the book would be W = Fd (7N)(2m) = 14 J

If the same 7 N book is slid under the bookcase 3 m away, with a pushing force of 5 N and a frictional opposing force of 2 N, then the work done is

F = F(push) - f(friction) = 5 N - 2 N = 3 N then W = Fd (3N)(3m) = 9 J

**OR**

should I be taking the 14 J from the first part and using

W = Fd = (14 J)(3m) = 42 J

Thank you for your help