The work done by the elephant to lift one log is the force multiplied by the height at which the log has been lifted:

And so, the total work done to lift the 7 logs is 7 times the work done to lift each log:
-- <span>The gravitational force that you feel when you stand on the surface
of a planet depends on the planet's mass and size. It has </span><span><span>nothing
to do with the planet's orbit. (</span>Of course,"size" is also related to the
planet's mass, density, and surface area.)
-- One possible cause of deforestation is the removal of trees without
adequate replanting.
-- According to Hubble’s Law, the farther away a galaxy is, the faster
it is moving away from us
-- Electromagnetic energy can be defined as energy that moves at
the speed of light. If you conduct experiments to determine whether
the electromagnetic energy is moving in the form of particles or waves,
you find that it behaves as both.</span>
Answer:
No, it is not proper to use an infinitely long cylinder model when finding the temperatures near the bottom or top surfaces of a cylinder.
Explanation:
A cylinder is said to be infinitely long when is of a sufficient length. Also, when the diameter of the cylinder is relatively small compared to the length, it is called infinitely long cylinder.
Cylindrical rods can also be treated as infinitely long when dealing with heat transfers at locations far from the top or bottom surfaces. However, it not proper to treat the cylinder as being infinitely long when:
* When the diameter and length are comparable (i.e have the same measurement)
When finding the temperatures near the bottom or top of a cylinder, it is NOT PROPER TO USE AN INFINITELY LONG CYLINDER because heat transfer at those locations can be two-dimensional.
Therefore, the answer to the question is NO, since it is not proper to use an infinitely long cylinder when finding temperatures near the bottom or top of a cylinder.
propagated disturbance is a variation
Answer: The light bends because light travels fast but it slows down in a denser medium. For example light refracts in water or it bends after passing through air. When light passes through air ( a less dense medium ) then through water ( a more dense medium ) the beam of light bends because light travels more slowly in a denser medium then it picks up its pace again once it passes. The density of the substance determines how much the light is refracted. I hope this makes sense and I hope this answered your question!! :)