| 摘要 |
Apparatus for demonstrating Newton's third law of motion comprises first and second substantially spherical masses. Structure is provided for moving first mass along a path of travel that includes substantially horizontal portion. Support structure is provided for locating second mass in alignment with horizontal portion of path of travel of first mass. Support structure includes vertically disposed support pin with flat support surface having area substantially less than diametral cross sectional area of second mass. Sleeve snugly surrounding support pin is mounted for sliding movement relative to pin, and weight is spaced from and directly above flat support surface of support pin for engaging top of second mass when second mass is positioned upon support surface of pin. Sleeve has upper position where upper surface thereof and support surface of pin are close to one another for locating second mass on support surface. Sleeve has lower position spaced from support surface of pin so that second mass is supported by pin between support surface thereof and weight when sleeve is moved to lower position after assisting in locating second mass on support surface.
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