Changes Made:

1. Disable step button when the end of the ramp is reached.
2.Indicate the height of the ramp
3. Resolve bug if end of the ramp is reached.
4. Change the inclination angle to the height of the ramp
5. Specify the material (hard code the coefficient of friction)
6. Show velocity/
7. Remove the unncessary forces

Maybe can consider using that for accessement. Let the students design an experiment to find out which material has the most friction.