Một vật trượt với vận tốc đầu 18 km/h xuống mặt phẳng nghiêng, vật trược nhanh dần đều với gia tốc 1.5 m/s^2s 2 . Dến mặt phẳng nghiêng đạt vận tốc 13 m/s và tiếp tục trượt trên mặt phẳng ngang. Hệ số ma sát trên mặt phẳng ngang là 0.2. Mặt phẳng nghiêng hợp với mặt phẳng ngang góc \alpha=30^0α=30 0 . Cho g=10m/s2. a. Tìm hệ số ma sát trên mặt phẳng nghiêng. b. Tìm chiều dài mặt phẳng nghiêng. c. Tính thời gian từ lúc vật bắt đầu trượt xuống mặt phẳng nghiêng đến lúc dừng lại

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