Calculate height given KE and mass

  • Thread starter Thread starter Sandman327
  • Start date Start date
  • Tags Tags
    Height Mass
Click For Summary

Homework Help Overview

The discussion revolves around calculating the height a nitrogen molecule would rise based on its kinetic energy (KE) and mass. The problem involves concepts from energy conservation, specifically the relationship between kinetic energy and potential energy (PE).

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to relate kinetic energy to potential energy using the equation U=mgy, expressing uncertainty about the connection between KE and U. Some participants suggest considering energy conservation principles, while others emphasize understanding the relationship between initial and final energy states.

Discussion Status

The discussion is active, with participants providing guidance on the energy conservation principle and acknowledging the original poster's calculations. There is a recognition of the importance of understanding the underlying concepts, although no consensus has been reached on the correctness of the height calculation.

Contextual Notes

Participants note that the nitrogen molecule is assumed not to lose energy by colliding with other molecules, which is a significant assumption in the context of the problem.

Sandman327
Messages
6
Reaction score
0

Homework Statement


At sea level a nitrogen molecule in the air has an average translational KE of 6.2x10-21 J. Its mass is 4.7x10-26 kg. If the molecule could shoot straight up without striking other air molecules, how high would it rise? Thanks for any help.

Homework Equations



I think to find height I should use the equation U=mgy but I'm not 100% sure because I don't understand how KE relates to U.

The Attempt at a Solution



I set the equation up so that y=U/mg and I get the answer 13460.7m which just seems to big to be right although I could be wrong about that.
 
Physics news on Phys.org
Draw a diagram of the initial and final states of the nitrogen molecule.
What's the energy in the initial state, and what's the energy in the final state? How do these two relate?

Your final answer is most likely correct (Number crunching errors aside), and I'm glad you see the importance of understanding how you got to it.
 
Last edited:
Welcome to PF!

Hi Sandman327! Welcome to PF! :smile:
Sandman327 said:
… I don't understand how KE relates to U.

It's very simple:

always remember this formula … KE + PE = constant :wink:
 
since it doesn't loose any energy by striking the other molecules, the entire KE will be converted into PE by raising to the height 13460.7m...
 

Similar threads

Find the height to which a mass rises
  • · Replies 3 ·
Replies
3
Views
1K
Calculate height and velocity given kinetic and potential?
  • · Replies 2 ·
Replies
2
Views
2K
Average Kinetic Energy of molecules calculation
  • · Replies 7 ·
Replies
7
Views
2K
The question: Can nitrogen molecules escape from Europa and into space?
  • · Replies 15 ·
Replies
15
Views
3K
Find the tension of a rope with a mass and spring attached
  • · Replies 4 ·
Replies
4
Views
2K
Calculating Initial Height of a Falling Safe on a Spring
  • · Replies 5 ·
Replies
5
Views
3K
Solving Pe + Ke Problem for Block of Mass m and Height h
  • · Replies 5 ·
Replies
5
Views
3K
Finding the Value of Gravity Given Height and Velocity
  • · Replies 9 ·
Replies
9
Views
4K
Starting height of marble rolling around a loop the loop
  • · Replies 12 ·
Replies
12
Views
13K
Equal Heights for Two Masses on a Spring: A Question of Energy?
  • · Replies 7 ·
Replies
7
Views
2K