Một cơn gió thổi qua làm rụng chiếc lá vàng xuống đất.Em hãy phân tích các lực tác dụng vào lá cây trước và sau khi rụng. Bài 4: Người ta chia ra hai loại lực: Lực tiếp xúc, lực không tiếp xúc. Em hãy phân loại các lực sau đây theo hai loại trên: lực ma sát, lực cản không khí, lực mà lò xo kéo vật lại, lực hút giữa mặt trời và trái đất, lúc hút gữa hai nam châm đặt xa nhau, lực mà gió tác dụng lên cánh buồm.

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