Work

[Shark 774]

Hey guys,

From the equation W = Fx it seems that if I apply a certain force higher in the atmosphere I will have done more work than if I apply that same force at sea level, because the object would travel further due to less air resistance. I don't think this can be right, but how do you explain this?

Thanks!

[xZero]

well if the object traveled further higher in the atmosphere than at sea level, the distance X is greater at the higher atmosphere and since the force is the same, the 1 with the greater distance traveled will require more work. Hope it makes sense :S

[/0]

can be somewhat misleading. is the distance through which the force is applied.

An example:
Suppose a block is standing still on a surface (not necessarily smooth). You draw a start line where the block is, and draw a finish line x metres away. Suppose you start pushing that block towards the finish line, applying constant force F throughout (your hand will also have to accelerate if you want to keep constant force on the block). Once the block reaches the finish line, you immediately remove your hand.
Then work you've done on the block is then .

It doesn't matter whether you're in a vacuum or the air is as thick as in a sauna. The work YOU do is the same each time, since you apply a force through a distance . It is irrelevant how much further the object goes after you remove your hand.

The reason why the object will travel less distance if there's more air resistance is because the AIR is doing work against the object as well.

[Shark 774]

can be somewhat misleading. is the distance through which the force is applied.

An example:
Suppose a block is standing still on a surface (not necessarily smooth). You draw a start line where the block is, and draw a finish line x metres away. Suppose you start pushing that block towards the finish line, applying constant force F throughout (your hand will also have to accelerate if you want to keep constant force on the block). Once the block reaches the finish line, you immediately remove your hand.
Then work you've done on the block is then .

It doesn't matter whether you're in a vacuum or the air is as thick as in a sauna. The work YOU do is the same each time, since you apply a force through a distance . It is irrelevant how much further the object goes after you remove your hand.

The reason why the object will travel less distance if there's more air resistance is because the AIR is doing work against the object as well.

Ok thanks! Pretty strange stuff to try and get your head around, but I think that all makes sense. Can't see any holes in my understanding of it now, as of yet... But we'll wait and see ha. Cheers.