Finding the speed before impact using the work-energy theorem

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To find the speed of a blue whale just before impact on an airless planet, the work-energy theorem is applied. The whale falls from a height of 11.5 km with a gravitational acceleration of 6.85 m/s². The work done by gravity equals the change in kinetic energy as the whale descends. By calculating the potential energy at the starting height and equating it to the kinetic energy just before impact, the final speed can be determined. This approach effectively utilizes the work-energy theorem to solve the problem.
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Homework Statement


A blue whale materializes 11.5 km above an airless planet with an acceleration of gravity of 6.85 m/s2. What is the speed of the whale right before impact? Use the work energy theorem.

Homework Equations



Work energy theorem : W = the change in k
W=kf - ko
w=1/2(mvf2) - 1/2(mvo2)
 
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So what force acts on the whale? How much work is done by that force as the whale falls to the surface?
 
Thread 'Correct statement about size of wire to produce larger extension'

Thread 'Correct statement about size of wire to produce larger extension'

The answer is (B) but I don't really understand why. Based on formula of Young Modulus: $$x=\frac{FL}{AE}$$ The second wire made of the same material so it means they have same Young Modulus. Larger extension means larger value of ##x## so to get larger value of ##x## we can increase ##F## and ##L## and decrease ##A## I am not sure whether there is change in ##F## for first and second wire so I will just assume ##F## does not change. It leaves (B) and (C) as possible options so why is (C)...
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