Which of the following astronomers was the first to propose elliptical orbits for the planets in our solar system?A.Brahe.Kepler
2 answers:
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Answer:
moving the boxes and the furniture up to the fifth floor.
Explanation:
The work done when moving an object up or down is equal to its change of gravitational potential energy:
where
m is the mass of the object
g is the gravitational acceleration
is the change in height of the object
We have two opposite situations:
1) when an object is moved upward, is positive, so the work done W is positive as well: this means that we need to do work in order to move the object, because we have to "win" the effect of gravity, which pulls the object downward
2) when an object is moved downward, is negative, so the work done W is negative as well: this means that we do not need to do work on the object, because it is already done by gravity, which pulls the object downward.
Therefore, more work is done when we are moving the boxes and the furniture up to the fifth floor.