Use the arrow keys ← → to step through. Arrows in the pictures: forces, velocities, accelerations and the net force.
The worked solution unlocks once you have solved the exercise, used all hints or made three attempts.
Nothing recorded yet. Wrong answers that stem from a misconception, and exercise types you find hard, will show up here.
How often each misconception was behind one of your wrong answers. The exercises are written in the spirit of the Force Concept Inventory; they are not its items.
Exercise types you found hard come up more often in practice, until you solve them easily.