Python 3.9.0 : Physics simulation with PyBullet .

I took a look at the documentation of this python packet to give you a brief introduction:
PyBullet is a fast and easy to use Python module for robotics simulation and machine learning, with a focus on sim-to-real transfer. With PyBullet you can load articulated bodies from URDF, SDF, MJCF and other file formats. PyBullet provides forward dynamics simulation, inverse dynamics computation, forward and inverse kinematics, collision detection and ray intersection queries. The Bullet Physics SDK includes PyBullet robotic examples such as a simulated Minitaur quadruped, humanoids running using TensorFlow inference and KUKA arms grasping objects.
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PyBullet can be easily used with TensorFlow and OpenAI Gym.
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The GUI connection will create a new graphical user interface (GUI) with 3D OpenGL rendering, within the same process space as PyBullet. On Linux and Windows this GUI runs in a separate thread, while on OSX it runs in the same thread due to operating system limitations.
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For UDP networking, there is a App_PhysicsServerUDP that listens to a certain UDP port.
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By default, there is no gravitational force enabled. setGravity lets you set the default gravity force for all objects. The loadURDF will send a command to the physics server to load a physics model from a Universal Robot Description File (URDF). The URDF file is used by the ROS project (Robot Operating System) to describe robots and other objects, it was created by the WillowGarage and the Open Source Robotics Foundation (OSRF).
I tested with Fedora 33 and Python version 3.9.0.
The first step was installation.

[mythcat@desk ~]$ pip3 install pybullet --upgrade --user
Collecting pybullet
  Downloading pybullet-3.0.6.tar.gz (89.8 MB)
     |████████████████████████████████| 89.8 MB 51 kB/s 
Using legacy 'setup.py install' for pybullet, since package 'wheel' is not installed.
Installing collected packages: pybullet
    Running setup.py install for pybullet ... done
Successfully installed pybullet-3.0.6

The next step was to test with examples already built using urdf file type.

import pybullet as p
# Can alternatively pass in p.DIRECT 
client = p.connect(p.GUI)
p.setGravity(0, 0, -10, physicsClientId=client) 

import pybullet_data
p.setAdditionalSearchPath(pybullet_data.getDataPath())
planeId = p.loadURDF("plane.urdf")

my_racecar = p.loadURDF("racecar/racecar.urdf", basePosition=[0,0,0.2])

position, orientation = p.getBasePositionAndOrientation(my_racecar)

for _ in range(10000): 
    p.stepSimulation()

I run the script and all works well.
It can be seen that in the cycle for which I have the simulation for 10000 steps of time.
A smaller number will quickly interrupt the simulation.
You can create your own URDF files because they are formatted in XML format.
A good area for learning is this webpage.