Câu 1: Tại sao trên đường bê tông người ta phải đổ bê tông thành từng tấm và đặt mỗi tấm cách nhau vài xentimet? ···················································································································· ···················································································································· ···················································································································· ····················································································································

Câu 2: Một chai nhựa rỗng được nút chặt, chai được đưa vào ngăn đá của tủ lạnh một lúc thì chai bị móp lại. Em hãy giải thích tại sao có hiện tượng trên. ···················································································································· ···················································································································· ···················································································································· ····················································································································

Câu 3: Tại sao người ta thường chế tạo tôn lợp mái nhà dạng hình gợn sóng mà không làm tôn phẳng ? ···················································································································· ···················································································································· ···················································································································· ····················································································································

Câu 4: Một lọ thuỷ tinh được đậy kín bằng nút thuỷ tinh. Khi nút bị kẹt, người ta thường nung nóng cổ lọ để có thể lấy cái nút ra dễ dàng . Em hãy giải thích nguyên tắc của cách làm trên? ···················································································································· ···················································································································· ···················································································································· ····················································································································

Câu 5: Ở đầu cán dao, liềm bằng gỗ, thường có một đai bằng sắt, gọi là cái khâu (Hình 1) dùng để giữ chặt lưỡi dao hay lưỡi liềm. Tại sao khi lắp khâu, người thợ rèn phải nung nóng khâu rồi mới lắp vào cán? ···················································································································· ···················································································································· ···················································································································· ····················································································································

Câu 6: Một người định đổ đầy nước vào một chai thuỷ tính rồi nút chặt lại rồi bỏ vào ngăn nước đá của tủ lạnh. Theo em, có nên làm như thế không ? Tại sao ? ···················································································································· ···················································································································· ·······································································································································································································································

Câu 7: Tại sao khi rót nước nóng ra khỏi phích nước rồi đậy nút lại ngay thì nút có thể bị bật ra ? Làm thế nào để tránh hiện tượng này ? ···················································································································· ···················································································································· ····················································································································

Câu 8: Khi cho bình cầu chứa khí (hình 2) vào chậu nước lạnh thì giọt nước màu sẽ di chuyển như thế nào? Giải thích hiện tượng đó.

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Câu 9: Quan sát nhiệt kế hình bên, ta thấy phần dưới mỗi thang đo có ghi oC và oF. Hãy cho biết: a) Việc ghi oC và oF có ý nghĩa gì? b) Ở thang nhiệt độ có ghi oC, thang nhiệt độ này có độ chia nhỏ nhất là bao nhiêu? Nhiệt kế đang chỉ bao nhiêu độ? ····························································································· ····························································································· ····························································································· ····························································································· ····························································································· ····························································································· ·····························································································

Câu 10: Nhiệt kế sử dụng theo nhiệt giai nào ? (hình bên) a) Nhiệt độ thấp nhất và cao nhất ghi trên nhiệt kế là bao nhiêu ? b) Nhiệt kế đang chỉ bao nhiêu độ ? ····························································································· ····························································································· ····························································································· ····························································································· ·····························································································

Hơi dài ạ,mong mọi ng thông cảm.Mọi ng ráng làm giúp mik với nhé.Thanks ạ.Có j k hiểu thì xem hình[ở dưới bình luận].Có j mik tặng 30 SP cho mấy bn làm đúng và nhanh nhé