Horizontal coefficient of restitution

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SUMMARY

The discussion centers on the determination of the horizontal coefficient of restitution (CoR) for a tennis ball, alongside the established vertical CoR of 0.760. The participant has successfully calculated the vertical CoR and is seeking guidance on the horizontal CoR, which is not commonly addressed in textbooks. It is concluded that while the horizontal CoR is not widely recognized, it can be derived similarly to the vertical CoR by utilizing the horizontal components of velocity. A reference to a physics paper suggests that the methodology for calculating the horizontal CoR mirrors that of the vertical CoR.

PREREQUISITES
  • Understanding of the coefficient of restitution and its significance in physics.
  • Familiarity with basic kinematics, particularly velocity components.
  • Knowledge of the relationship between height and velocity in elastic collisions.
  • Access to physics resources or textbooks that cover collision mechanics.
NEXT STEPS
  • Research the derivation of the horizontal coefficient of restitution using horizontal velocity components.
  • Study the relationship between vertical and horizontal motion in elastic collisions.
  • Examine the physics paper referenced in the discussion for detailed methodologies.
  • Explore practical experiments to measure both vertical and horizontal coefficients of restitution in real-world scenarios.
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and collision theory, as well as educators seeking to clarify concepts related to the coefficient of restitution.

Psych Berry
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Homework Statement


I'm supposed to determine the [vertical] coefficient of restitution of a tennis ball, and the horrizontal coefficient of restitution, and if possible produce an equation or ratio connecting the two.

Vertical CoR: 0.760
Constant x-component velocity: 0.853 m/s

Homework Equations


sqrt (h2/h1) = |v2/v1|


The Attempt at a Solution


I've already calculated the [vertical] coefficient of restitution, and googled to find out that my answer is consistent with that of standard tennis ball.
At this point I just don't know how to calculate the horrizontal CoR. My textbook and lab manual don't mention it, and I can't figure out what relationship they would have.
Can anyone help me out here?
 
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From what I am told, the coefficient of restitution for when objects collide in two planes, is found by taking the ratio of the vertical component of the velocities. So I don't think there is such thing as a horizontal coefficient of restitution.
 
rock.freak667 said:
From what I am told, the coefficient of restitution for when objects collide in two planes, is found by taking the ratio of the vertical component of the velocities. So I don't think there is such thing as a horizontal coefficient of restitution.

Maybe that's true, my lab manual where the questions are stated is definitely not written by people with doctorates in physics. But that's merely terminology. It wouldn't change my question.

If there is no such thing as "horizontal coefficient of restitution" then what would the corresponding horizontal ratio be?

Thinking about it more I assume it would be based off the regular coefficient of restitution, since horizontal velocity is constant, therefore the distance traveled per bounce is a function of time, and the time of each bounce is dependent on the max height reached, which is in turn dependent on the CoR. But I don't know how to state that in an equation, or if I'm even on the right track.
 
hi rock.freak667! :smile:

yeah, I've never heard of it before either …

but I just googled it, and apparently it does exist (I couldn't be bothered to read about it though :rolleyes:)
 
tiny-tim said:
hi rock.freak667! :smile:

yeah, I've never heard of it before either …

but I just googled it, and apparently it does exist (I couldn't be bothered to read about it though :rolleyes:)

Well then, if it exists can anyone enlighten me as to how to obtain it?
 
Psych Berry said:
Well then, if it exists can anyone enlighten me as to how to obtain it?

Well according to http://www2.physics.umd.edu/~mfuhrer/course/spr02/AJP/AJP00482.pdf" , it seems that you obtain the horizontal coefficient of restitution the same way you get the vertical one. You just use the horizontal components instead of the vertical ones it seems.
 
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The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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