Physics

Classical Mechanics Level 2

A person falls freely towards earth. If air friction is considered, then what happens to the total energy of this person?

Decreases First increases and then decreases Remains constant Increases

Ankit Vijay by Ankit Vijay , 22, India

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3 solutions

Mohamed Husain
Jun 13, 2014

If a object falls due to friction it loss its energy, like moving a table in a hard(friction) surface. This is the reason that many asteroids entering earth losses its energy due to the friction by the air and finally disappears.

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But when the object gets more near to earth, the more acceleration is observed in the object.

Shubham Gaikwad - 6 years, 12 months ago

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when object is near to earth it'"s potential energy is much less in comparison to K.E.

VISHAL YASH - 6 years, 11 months ago

The acceleration is almost the same,if you consider an ideal case where there is no air and you drop a ball then total energy is conserved but the drag in this case causes a loss in energy as heat.Therefore energy get reduced.

Jacob Sony - 5 years, 9 months ago
Hanif Robbani
Aug 1, 2014

According to law of conservation of energy, total energy of this person is his potential energy plus kinetic energy. Taking friction into account, person's velocity doesn't increase enough to make his kinetic energy able to balances amount of potential energy loss during his falling movement. So we can conclude that total energy of this person is decreasing.

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based on law of conservation of energy , E(start)=E(end) K(start)+U(start)=K(end)+U(end)+|(Work air friction)| => U(start)=K(end)+ |W|

Ep1=U(start) , Ep2=K(end) => Ep2-Ep1=K(end)-U(start)=-|W|<0 So, the total energy is decreased

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