Please try my free courses on Coursera as a help with Dynamics.
Here are the links:
Dynamics-Part 1 (2D): https://www.coursera.org/learn/dynamics
Dynamics - Part 2 (3D): https://www.coursera.org/learn/motion-and-kinetics
If you need help with Statics or Mechanics of Materials, I also have these courses available:
Statics-Part 1: https://www.coursera.org/learn/engineering-mechanics-statics
Statics-Part 2: https://www.coursera.org/learn/engineering-mechanics-statics-2
Mechanics of Materials I: Fundamentals of Stress and Strain and Axial Loading: https://www.coursera.org/learn/mechanics-1
Mechanics of Material II: Thin walled Pressure Vessels and Torsion: https://www.coursera.org/learn/mechanics2
Mechanics of Materials III: Beam Bending: https://www.coursera.org/learn/beam-bending
Mechanics of Material IV: Deflections, Buckling, Combined Loading, and Failure Theories: https://www.coursera.org/learn/materials-structures
NOTE: - Yes, these courses are free! You can pay $49 for a certificate if you want, but it is in no way obligatory.
I hope you find this material useful. If so, please tell your friends about this resource.