Jimmy has two options for moving a piano up to the second floor of a hotel, which is 10 m above his current position. He can push the piano up 50 m ramp or lift the piano up with a rope wrapped around a pulley. Which option will require him to exert a greater average force? Neglecting friction, which option will require more work?

Lifting straight up, even with a rope and pulley, always takes more force than going up a slanted ramp to the same height.

But if you use the ramp, then you have to exert the force over a greater distance (pull more rope to lift to the same height).

Astonishingly, the product of (force) x (distance) is the same number either way.  So without friction, the total amount of work required is the SAME whichever way the piano is lifted.

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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