# Capturing the physics of bouncing in a simulation

• mindbreaker
In summary: For high-enough friction and low-enough elasticity, you can get a situation where the ball bounces at an angle, then rolls without bouncing again.In summary, the conversation discusses the concept of elasticity in regards to programming a bouncing object. The speaker mentions wanting the object to bounce differently based on its texture and the need to consider friction. The concept of elasticity is defined as a measure of the amount of kinetic energy that can be recovered during a collision and is represented by a number between 0 and 1. The presence of friction can complicate the bouncing motion by causing a ball to spin upon impact.
mindbreaker
hi,
srr if this isn't the wright place to post this...

I'm working on engine (i'm a programer , c++) and I'm stuck at bouncing...

I have an object (repressented by a sphere) at an unknow hight, with an unknow mass and I drop it, so gravity does it job and it starts to fall down

now , when there is a collision with the floor, I want the object to bounce but dependent of it's texture ( ex.: tennisball - bowl ball ) and physical correct ...
how is this done ? I remember I saw this (almost 8 years ago ) at school ...

note 1: friction (etc) can be ignored (for now , so if this isn't must harder i request this already )
note 2 : this is something that should take place at Earth and at a normal height (so not 150 km above into the sky ) ...

thx anyway

You can give the object a property called "elasticity". "Elasticity" is a measure of the amount of kinetic energy that can be recovered when the object has deformed due to collision; springier substances that can return to their original shape are more elastic (bowling balls, tennis balls, steel balls and rubber balls are all very elastic; balls of Silly-Putty are very inelastic).

Practically speaking, elasticity is a number between 0 and 1 that represents the fraction of energy retained in collisions. A ball of elasticity 1 will bounce up to its original height every time; a ball of elasticity 0 will fall and then stick to the ground, without bouncing at all. Most objects are somewhere in between; a ball of elasticity 0.8 will always bounce up to 80% of its previous height (thus, the bounces will decrease in height exponentially).

In the case of nonzero friction, you have an additional complication: a ball striking a surface at a glancing angle will, due to friction, experience a torque causing it to spin. Thus, some of the previous translational kinetic energy gets converted into rotational kinetic energy.

Hi there,

I can provide some insights on how to capture the physics of bouncing in a simulation. First, it's important to understand the basic principles of bouncing. When an object falls and hits the ground, it experiences a force from the ground that causes it to change direction and move upwards again. This force is known as the normal force and is dependent on the object's mass and the surface it is bouncing off of.

In order to accurately simulate this in your program, you will need to incorporate the equations for calculating the normal force and the force of gravity. These can be found in any basic physics textbook or online resource. Additionally, you will need to consider the properties of the object, such as its mass, elasticity, and surface texture.

For example, a tennis ball is more elastic than a bowling ball, so it will bounce back higher when dropped from the same height. This is because the elastic properties of the tennis ball allow it to store more energy upon impact and release it as it bounces. In your simulation, you can incorporate this by adjusting the elasticity of the object based on its texture.

It's also important to consider air resistance, as this can affect the object's trajectory and the force of impact on the ground. However, since you mentioned that friction can be ignored for now, you can leave this out of your simulation.

Overall, simulating bouncing accurately can be a complex task, but by incorporating the basic principles of physics and considering the properties of the object, you can create a realistic simulation. I hope this helps and good luck with your project!

## 1. What are the main factors that affect bouncing in a simulation?

The main factors that affect bouncing in a simulation include the elasticity of the bouncing object, the surface it is bouncing on, and the initial velocity and angle of the bounce.

## 2. How is the physics of bouncing represented in a simulation?

In a simulation, the physics of bouncing is typically represented through mathematical equations that take into account the forces acting on the object, such as gravity and elastic forces, and the object's properties, such as mass and elasticity.

## 3. Can different materials be simulated to bounce differently?

Yes, in a simulation, different materials can be given different properties that affect their bouncing behavior. For example, a rubber ball will bounce differently than a steel ball due to differences in their elasticity and mass.

## 4. How does air resistance affect bouncing in a simulation?

Air resistance can affect the height and distance of a bounce in a simulation, as it creates a force that opposes the motion of the object. This force is typically accounted for in the simulation through equations that take into account the velocity and surface area of the object.

## 5. How accurate are simulations in capturing the physics of bouncing?

The accuracy of simulations in capturing the physics of bouncing can vary depending on the complexity of the simulation and the accuracy of the input parameters and equations used. In general, simulations can provide a good approximation of the physics of bouncing, but they may not perfectly replicate real-world scenarios.

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