# Need help with physic materials

I am trying to create a few different physic materials to simulate different types of ground, but the values on the physic materials don’t seem to matter (other than bounciness, which isn’t want I’m looking for.)

To test my hypothesis, I set up 5 planes, each at the same slope (rotated the z axis 3 degrees, and I set 5 identical spheres with rigid-bodies at the top of the planes. I then applied 5 different physicals materials with values for dynamic and static friction ranging from 0 to 1, and then observed them rolling down the slope. They rolled at the exact same speed.

For a final test, I gave the balls their own identical physics materials, and they still rolled at the same speed. Shouldn’t higher friction be slowing these balls down?

The end goal is to have different materials such as sand, that would stop a rolling ball very quickly, while having other materials that would slow a ball down slower.

I know you can adjust the angular drag of a ball to make it slow its rotation, but that is dependent on the ball, which is a not a solution, as I need the same ball to behave differently on different physics materials.

For reference, Unity’s Dynamic friction description: “The friction used when already moving. Usually a value from 0 to 1. A value of zero feels like ice, a value of 1 will make it come to rest very quickly unless a lot of force or gravity pushes the object.”

The value is set to 1 on one of the platforms, and the slope is very slight, yet the ball continues to roll…

Edit finding the “friction” tag gave me some more answers: If I lock rotation on a ball, it seems to have some effect, but this is not a solution I can use, as I NEED rotation. Any suggestions on having rotation + also having varying friction levels?

The solution I can currently think of is to Raycast down, get the material type if it is on the ground, and then run my own simulation of slowing down its velocity and angular velocity based on the material type. I would however prefer to get this working using a physics material…

Friction has a lot less effect on balls. A real ball covered with sandpaper, rolling on sandpaper, is going to roll about the same as a marble on glass. If you try with a cube or (angled) capsule, you’ll see the effect a lot more.

Dropping the objects is only testing dynamic friction. To test static, place objects resting on the planes. Some will slide down, some will stick, and some of the sticky ones will need a big hit to get moving (high static and low dynamic will seem like it “breaks loose”.)

Can’t tell for sure if you did this, but the surface and ball should each have a physics mat. It works when one doesn’t, but the numbers act funny.