Forces are INTERACTIONS
Have fun exploring this concept with the various setups :-)
When you're all done, hopefully these mean something to you...
1 Inertia 2 a=F/m 3 Fab = -Fba
Understand those, truly understand those, and you know a ridiculous amount of physics.
Don't get caught in the common misconceptions, (which we've chatted about 342 times ;-)