A couple of things first:
- Always use code-tags when posting code (please edit your post)
- State what the problem actually is and ask a specific question
It looks like you’re just guessing at how things work because you seem to be using 2D physics but are also using 3D physics callbacks. Watching at least a single 2D physics tutorial would show you this. It also looks like you’re struggling to understand how to write code, which is fine, but you’re asking for “insight”.
The following isn’t valid code for instance (ignoring that it’s a 3D physics callback).
OnCollisionEnter(Collision other) {
Speed * 1;
}