How come a bouncing ball does not exhibit SHM characteristics?

In summary, the reason why a bouncing ball does not exhibit SHM characteristics is because it lacks a restoring force, which is essential for SHM. The contact force with the ground disrupts the constant accelerated motion of the ball, making it unable to return to its original position. Even in a hypothetical scenario where there is no loss of energy during the bounces, the lack of a restoring force would still prevent it from exhibiting SHM.
  • #1
.NoStyle
35
0

Homework Statement


How come a bouncing ball does not exhibit SHM characteristics?


Homework Equations


no clue



The Attempt at a Solution



When I think of SHM, I don't think of contact forces. In the bouncing call case, there is a contact force present when the ball hits the ground.

Would the graph for a bouncing ball look curved as it approached it's height, but then a sharp V as it hits the ground?

Thanks
 
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  • #2
What is the defining characteristic of a system in SHM? Does this apply to a bouncing ball?
 
  • #3
Think of it this way...

As the ball bounces, why do the time intervals that the ball is in the air get smaller the longer the ball bounces... it is missing a certain force that is essential to SHM...
 
  • #4
The fact that the ball is airborne for shorter periods of times after each consecutive bounce is not the reason why it doesn't count as SHM. One can envisage a hypothetical scenario where the collision of the ball with the floor is entirely elastic; no kinetic energy is lost to the floor as heat, sound etc. There is something more fundamental in the definition of SHM than that consideration.
 
  • #5
Defennder said:
The fact that the ball is airborne for shorter periods of times after each consecutive bounce is not the reason why it doesn't count as SHM. One can envisage a hypothetical scenario where the collision of the ball with the floor is entirely elastic; no kinetic energy is lost to the floor as heat, sound etc. There is something more fundamental in the definition of SHM than that consideration.

maybe were on a different wavelength here, but i was hinting at... its not SHM because it has no restoring force... aka... why the ball doesn't return to its original position. I wasnt saying that's why it isn't SHM, i was using that as an example as to aid him in finding the answer.
 
  • #6
.NoStyle said:

Homework Statement


How come a bouncing ball does not exhibit SHM characteristics?

Homework Equations


no clue

The Attempt at a Solution



When I think of SHM, I don't think of contact forces. In the bouncing call case, there is a contact force present when the ball hits the ground.

Would the graph for a bouncing ball look curved as it approached it's height, but then a sharp V as it hits the ground?

(By the way, a bouncing ball that is in motion in another direction exhibits what you describe with the sharp V at the impulse of the floor changing direction.

Thanks
From Wikipedia:
"In words, simple harmonic motion is "motion where the force acting on a body and thereby acceleration of the body is proportional to, and opposite in direction to the displacement from its equilibrium position" (i.e. F = − kx)."

Your instinct looks correct. The contact with the floor is an impulse force that perturbs the constant accelerated motion that it is otherwise subjected to in one direction of gravity only.)
 

Related to How come a bouncing ball does not exhibit SHM characteristics?

1. Why does a bouncing ball not exhibit simple harmonic motion (SHM) characteristics?

The main reason a bouncing ball does not exhibit SHM characteristics is because it does not follow the conditions necessary for SHM. In order for an object to exhibit SHM, it must have a restoring force that is directly proportional to the displacement from equilibrium and acts in the opposite direction of the displacement. However, in the case of a bouncing ball, the restoring force (gravity) is not directly proportional to the displacement and also changes direction as the ball bounces, making it impossible for the ball to exhibit SHM.

2. Can a bouncing ball ever exhibit SHM?

In theory, it is possible for a bouncing ball to exhibit SHM if it meets the necessary conditions. This would require the ball to have a perfectly elastic surface, constant gravitational force, and a perfectly flat and level surface to bounce on. However, in real-world scenarios, these conditions are rarely met, so a bouncing ball typically does not exhibit SHM.

3. How does air resistance affect a bouncing ball's motion?

Air resistance plays a significant role in a bouncing ball's motion. As the ball bounces, it experiences air resistance which causes it to lose energy and therefore bounce lower with each subsequent bounce. This is why a ball will eventually come to rest on the ground, rather than bouncing indefinitely in a perfect SHM pattern.

4. Is a bouncing ball considered a form of periodic motion?

Technically, yes, a bouncing ball can be considered a form of periodic motion because it repeats the same motion over and over again. However, it is not considered simple harmonic motion since it does not follow the necessary conditions for SHM.

5. What factors can affect the bounce of a ball?

Several factors can affect the bounce of a ball, including the material and elasticity of the ball, the surface it bounces on, and external forces like air resistance and friction. The height and angle at which the ball is dropped can also affect its bounce. Additionally, factors like temperature and air pressure can also play a role in the bounce of a ball.

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