# Precision of a sphere impact and velocity forces

• donwhitson
In summary, a police officer specializing in less lethal weapons has asked for help in understanding why their projectiles veer off target with higher velocities. The answer lies in the Magnus effect, which occurs when a spinning object experiences uneven air pressure and is forced off course in the direction of its spin. This explains why the PepperBall projectiles are more accurate at lower velocities.
donwhitson
I am a police officer specializing in less lethal weapons. This question has come up many times and is beyond my understanding of physics to explain it. Please help:

We use a tool called a PepperBall. It is the same shape and diameter of a paintball. This sphere however is rigid plastic instead of the flexible paintball rubber. When it impacts the sphere breaks, releasing a pharmaceutical grade pepper powder. This powder is an irritant to the human eyes, nose, lungs and so on.

The projectile is fired from an air compressed launcher- similar to a paintball gun. The projectiles are launched at (+ or -) 350 feet per second. We have found through altering the air pressure we can increase the velocity of the projectile to over 500 feet per second. However, at about 400-425 feet per second the round projectile starts veering off target and looks like a knuckleball for lack of a better explanation. At 275-350 feet per second the round is generally point of aim-point of impact at constant distances.

We have controlled the variables we can such as shooting them inside with little to no wind. We have also tried to shoot them in similar conditions such as relative humidity. But for some reason these veer off target dramatically with higher velocities. The mass of the projectile is constant at about 4 grams.

Can anyone explain in relative lay terms what causes a spherical object to be less accurate and veer off in flight with higher velocities? Thanks for your time. I will include attributions to anyone that can help me understand this phenomenon.

The phenomenon you are seeing is called a Magnus effect. A Magnus effect occurs when a spinning object moves through the air, and an uneven force is generated on the object due to the difference in air pressure on either side of it. This force causes the object to veer off course and move in the direction of the spin. The faster the object is moving, the greater the Magnus effect. In the case of the PepperBall, the projectile is spinning as it is fired from the gun, and the Magnus effect causes it to veer off course as the velocity increases. This is why the projectile is more accurate at lower velocities. Hope this helps!

## 1. What is the precision of a sphere impact?

The precision of a sphere impact refers to the accuracy with which a sphere hits its intended target. It can be measured by the amount of deviation from the desired point of impact.

## 2. How is the precision of a sphere impact calculated?

The precision of a sphere impact is typically calculated by measuring the distance between the actual point of impact and the desired point of impact, and then dividing it by the desired distance.

## 3. What factors affect the precision of a sphere impact?

The precision of a sphere impact can be affected by factors such as the shape and material of the sphere, the force of impact, and external factors like air resistance or surface irregularities.

## 4. What is the relationship between velocity and force in a sphere impact?

The velocity and force in a sphere impact are directly related. This means that as the velocity of the sphere increases, so does the force of impact. Similarly, when the velocity decreases, the force of impact also decreases.

## 5. How can the precision of a sphere impact be improved?

The precision of a sphere impact can be improved by using a more precise and uniform sphere, controlling external factors that may affect the trajectory of the sphere, and adjusting the force of impact to achieve the desired precision.

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