Start an empty wagon and a loaded wagon at matching lines. Give each the same headed pull: the empty wagon travels farther.
Tap the push. Equal arrows with clear right-pointing heads strike a light and heavy block in the controlled model.
Change mass while force stays fixed. The acceleration meter follows force divided by mass.
Tap between two right-pointing pushes. The stronger arrow grows but stops before the block; watch the ratio, not just one number.
Cart A gets force four with mass two. Cart B gets force eight with mass four.
Cart A: force 4, mass 2. Cart B: force 8, mass 4.
Which cart gains speed faster?
Choose, then hold both pushes and watch the two carts travel from their matched starts.