I'm a bit confused about the difference in calculating work done in vertical and horizontal directions.
WorkDone = Force x DistanceMoved. For forces in a vertical direction the WorkDone is equal to the gravitational potential energy gained. So, the work done lifting a 2kg book through 1.5m is (about) 30 J.
Some books will ask questions of the form: how much work is required to move a 2kg across a 1.5m table? If the book has a weight of (about) 20 N then the answer we arrive at is 30 J.
But intuitively, it is (normally) easier to move things across than it is up - the answers shouldn't be equal.
So am I right in saying that the weight of the book isn't, on its own, important for calculating work done moving the book across the table? And that, in addition, for example, we would need things like surface area, friction per unit of surface area? In other words, it is the force required to move the book rather than weight of the book that is important?
2007-02-18
01:55:09
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4 answers
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asked by
Grant V
1
in
Physics