🛒 Forces and motion: give it a push

Unit 2 · Matter, forces & life · 10 min

Forces change motion. Equal and opposite forces cancel: the object stays still or keeps moving steadily (Newton’s first law). A bigger net force means more acceleration; a heavier object is harder to speed up (F = m·a). Friction always resists motion.

Words in this lesson

• 力 (lì) — force
• 摩擦力 (mócālì) — friction
• 加速度 (jiāsùdù) — acceleration

Project: Push the same toy car on tile, carpet and a table top and compare how far it rolls.