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
Tạm thời các bạn cứ né mấy câu 5,8,9,10 nhé.Vì mik chưa gửi ảnh được
Xin trân trọng cảm ơn
Câu 1: Câu hỏi của Nguyễn Thế Anh - Vật lý lớp 6 | Học trực tuyến
Câu 3; Câu hỏi của Nguyen Phuong Uyen - Vật lý lớp 6 | Học trực tuyến
Câu 2: Kết quả tìm kiếm | Học trực tuyến
Câu 4: Kết quả tìm kiếm | Học trực tuyến
Câu 5 : Bài C5 trang 59 SGK Vật lí 6 - loigiaihay.com
Câu 6: Câu hỏi của Huỳnh Minh Nghi - Vật lý lớp 6 | Học trực tuyến
Câu 7: Câu hỏi của Anh Nguyen - Vật lý lớp 6 | Học trực tuyến
Câu1
Vì mùa hè, bê tông nở ra, các khe sẽ khích lại. Còn mùa đông, bê tông co lại, các khe sẽ về chỗ cũ như ban đầu. Nếu không để như vậy, khi bê tông nở, nó sẽ gây một lực khiến đường gập ghềnh.
câu 2:
Khi đưa vào tủ lạnh, nhiệt độ của nước và phần không khí chứa trong chai (do không đầy nước) giảm xuống. Nhưng thể tích của khối không khí và khối nước mặc dù có thay đổi nhưng rất ít, ta xem thể tích bằng hằng số (đẳng tích). Khi nhiệt độ giảm theo quá trình đẳng tích thì áp suất giảm theo. Và do đó áp suất bên ngoài lúc này lớn hơn nén chai lại làm nó bị móp méo.
câu 3:
Khi trời nắng nóng hoặc nhiệt độ môi trường cao, các tấm tôn sẽ nở dài ra, nếu như mái tôn thẳng không có hình gợn sóng thì các cây đinh sẽ bị bung ra do sự nở vì nhiệt của tấm tôn, còn nếu như mái tôn được uốn cong hình gợn sóng thì nó sẽ tạo lực để làm cong thêm nếp uốn nhưng sẽ không hư hại gì cho tấm tôn.
câu 4:
vì chất rắn nở ra khi nóng lên, co lại khi lạnh đi nên khi đun nóng cổ lọ, thủy tinh là chất rắn nên cổ lọ sẽ nở ra, nút nhỏ hơn nên dẽ dàng tháo ra khỏi lọ
câu5:
Khi lắp khâu sắt vào cán dao, liềm bằng gỗ, người thợ rèn phải nung nóng khâu để khâu nở ra dễ dàng lắp được vào cán, khi nguội đi khâu co lại bám chặt vào cán dao làm cho dao, liềm được gắn chặt vào cán hơn.
câu 6:
KHÔng,Vì nước và thuỷ tinh nở vì nhiệt khác nhau,do đó sẽ cùng tác dụng lực lên nhau,gây nên bị vỡ.Mà bình thuỷ tinh lại bị đậy kín nên có thể dẫn đến làm nổ bình,có thể gây thương tích.
câu7:
Khi rót nước nóng ra có một lượng không khí ở ngoài tràn vào phích . Nếu đậy nút ngay thì lượng khí sẽ bị nước trong phích làm cho nóng lên , nở ra và có thể làm bật nút phích . Để tránh hiện tượng này , không nên đậy nút ngay mà chờ cho lượng khí tràn vào phích nóng lên , nở ra và thoát ra một phần mới đóng nút lại .
cau 5:Ở đầu cán (chuôi) dao, liềm bằng gỗ, thường có một đai bằng sắt, gọi là cái khâu dùng để giữ chặt lưỡi dao hay lưỡi liềm. Tại sao khi lắp khâu, người thợ rèn phải nung nóng khâu rồi mới tra vào cán?
Hướng dẫn giải:
Phải nung nóng khâu dao, liềm vì khi được nung nóng, khâu nở ra để lắp vào cán, khi nguội đi khâu co lại siết chặt vào cán
