## ketz 3 years ago What is the Internal energy of a falling ball??

1. shivam_bhalla

@experimentX , @Siddharth18 , Is Internal energy = Potential energy??

2. Siddharth18

@ketz is the question in context of mechanics or thermodynamics?

3. ketz

Thermodynamics question!

4. Siddharth18

if that's the case then i guess @shivam_bhalla has got it right

5. shivam_bhalla

I would say , do you want to consider friction and other viscous force in air? If yes, then falling ball internal energy increases

6. ketz

I think it has zero internal energy since there is no change in the kinetic and potential energies of the molecules found inside the ball!!!

7. ketz

ΔU=0 I think!

8. Siddharth18

but one thing confuses me we have considered only the gravitational potential energy but what about the bond energy and static electric energy which constitute the total potential energy of the system

9. Siddharth18

@ketz if u luk from an inertial frame ,the molecules will be having KE

10. shivam_bhalla

@Siddharth18 is absolutely right :)

11. shivam_bhalla

Looks like you are still not convinved @ketz . Imagine you are sitting in a train and you are seeing a passenger sit next to you . For you he appears stationary. Why?? because you are viewing from non-inertial reference. If you are looking from ground, you will see the passenger moving(i.e having Kinetic energy). Hopefully this brings clarity to you

12. Vincent-Lyon.Fr

Hi! Better go back to definitions! Have a look at the words at the end of the second sentence. This is why internal energy is called 'internal'! http://en.wikipedia.org/wiki/Internal_energy

13. shivam_bhalla

@Vincent-Lyon.Fr , looks like you are right and I am wrong . :D . and the answer to the question is zero @ketz

14. Vincent-Lyon.Fr

@shivam_bhalla: You gave the answer to the question: "What is the CHANGE in internal energy for a falling ball" The question was : "What is the Internal energy of a falling ball?" So the answer must be: "The same as when it is at rest".

Find more explanations on OpenStudy