# Qualitative collisions questions

• goobertron
In summary, the smaller ball is likely to detach from the larger ball if it hits a wall at a high speed.
goobertron
Hello all. I have what seems to be a fairly simple problem but I need a bit of help on the reasoning and what happens in a qualitative sense if some factors change.

The problem is of e.g. a larger spherical type thing happily traveling along at a fixed velocity but with a smaller (e.g. 10x smaller by diameter) sphere adhered to the surface. This large/small pair now hits a surface.

What is the likelihood of detachment based on? I am thinking it is a function of the mass of the smaller particle and the deceleration of the combo pair as it hits the wall (i.e. if the F=ma in this scenario exceeds the adhesion force then the smaller thing detaches?)

Now, keep the smaller sphere the same size but increase the larger sphere (lets assume the same force of adhesion between the pair to keep it simple). If traveling at the same velocity as before it seems like there should be a greater chance of detachment, but is this because of momentum exchange? As you can see my Physics here is shocking!

If someone could sort out this basic issue first I'd then like to expand slightly.

Thanks!

I doubt they'll detach if they're glued.

If I understand correctly, the smaller ball is attached to the back of the larger ball and the larger ball hits the wall. In this case, yes the smaller ball will feel a greater force upon impact the more massive the larger ball because of momentum transfer. You can do this experiment very easily. Hold a large exercise ball a few inches off the ground with a tennis ball resting on top and let go. When they both fall due to gravity and hit the ground, the tennis ball with go rocketing up into the air at a surprisingly high speed. This is a fun demonstration because the balls don't pick up much speed before they hit the ground, yet the tennis ball gains a great speed on impact. It demonstrates that total velocity is not conversed, only total momentum. When a high-mass, low-velocity object transfers its momentum to a low-mass object you get high velocity!

Thanks Chris - what about if it was stuck to the side? Does a larger or smaller parent ball give a more likely qualitative detachment force?

I would approach this problem by first defining the variables and factors involved. In this case, we have the mass of the smaller particle, the deceleration of the combo pair, and the force of adhesion between the pair. These factors will determine the likelihood of detachment when the pair hits a surface.

Based on the concept of Newton's second law of motion (F=ma), it is likely that if the deceleration of the pair exceeds the adhesion force, the smaller particle will detach from the larger one. This is because the force of deceleration will be greater than the force of adhesion, causing the smaller particle to overcome the attraction and detach.

When we increase the size of the larger sphere while keeping the smaller one the same, the mass of the combo pair will increase. This means that the force of deceleration will also increase, making it more likely for the smaller particle to detach upon impact with the surface. This is due to the principle of momentum exchange, where the larger mass will transfer more momentum to the smaller particle upon impact.

To expand on this problem, we could also consider the surface properties of the larger sphere and the surface it is impacting. For example, if the surface is rougher, the force of adhesion may be stronger, making it less likely for the smaller particle to detach. Additionally, we could also consider the speed and angle of impact, as these factors can also affect the likelihood of detachment.

In conclusion, the likelihood of detachment in this scenario is dependent on multiple factors such as mass, deceleration, and force of adhesion. By understanding these factors and their relationship, we can better predict and explain the outcome of this qualitative collision.

## 1. What is meant by "qualitative collisions" in physics?

Qualitative collisions refer to collisions between objects in which the forces involved are not quantitatively measured. Instead, the focus is on the overall outcome of the collision and the changes in motion of the objects involved.

## 2. How are qualitative collisions different from quantitative collisions?

The main difference between qualitative and quantitative collisions is the level of detail in the analysis. In qualitative collisions, only the overall outcome is considered, while in quantitative collisions, precise measurements of forces, velocities, and other variables are taken into account.

## 3. What types of collisions are typically studied using qualitative methods?

Qualitative collisions are commonly studied in macroscopic physics, such as in the motion of cars or balls. They are also used in the study of gas particles in thermodynamics and in astronomy, such as in the formation of galaxies.

## 4. How can qualitative collisions be useful in scientific research?

Qualitative collisions allow for a simplified understanding of complex interactions between objects and can provide insights into the behavior of systems without the need for precise measurements. They can also serve as a starting point for further investigation and experimentation.

## 5. Are qualitative collisions an accurate representation of real-world collisions?

While qualitative collisions may not provide the same level of precision as quantitative methods, they can still accurately describe the overall outcome of collisions in real-world scenarios. They can also help to identify important factors and variables that may affect the outcome of a collision.

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