A limb with mass 14 kg falls out of a tree from a height of 3.5 m. How much mechanical energy does the limb have just before it hits the ground? (Assume there is no air resistance.) A. 480.2 J B. 355.3 J C. 0 J D. 49 J

Question

Physics

Sandra Peck

29 April, 15:38

A limb with mass 14 kg falls out of a tree from a height of 3.5 m. How much mechanical energy does the limb have just before it hits the ground? (Assume there is no air resistance.) A. 480.2 J B. 355.3 J C. 0 J D. 49 J

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Answers (1)

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Adolfo Garner · Answer 1

While the limb is still on the tree on the height h=3.5 m, it has only potential energy Ep=m*g*h where m is the mass, g=9.81 m/s² and h is the height. While it is falling down its potential energy is converting into kinetic energy Ek = (1/2) * m*v², where m is mass and v is the velocity. The moment before it hits the ground the entire potential energy is converted into kinetic energy:

Ek=Ep=m*g*h=14*9.81*3.5=480.69 J.

So the correct answer is A. 480.2 J