Một tàu hoả đang di chuyển với vận tốc 54 km/h thì tài xế hãm phanh để xe chuyển động chậm dần đều. Sau khi đi thêm được 50m thì vận tốc của nó là 36km/h a) Tính gia tốc của tàu b) Tính quãng đường mà đoàn tàu đi được kể từ khi phanh đến khi nó dừng lại C) Tính vận tốc của đoàn tàu khi nó đi được 25m kể từ khi bắt đầu hãm phanh

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