KT VL8 1 tiết

Họ và tên: ................................................. ĐỀ KIỂM TRA VẬT LÍ 8
Lớp:8/ Thời gian làm bài : 45 phút ( Không kể thời gian phát đề )

Điểm





Lời nhận xét của Thầy giáo






I. Lý thuyết : (7,5 điểm )
Câu 1: Nhiệt lượng là gì? Đơn vị nhiệt lượng? (1,0đ)
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Câu 2: Tại sao về mùa đông mặc nhiều áo mỏng lại ấm hơn mặc một áo dày? (2,0đ)
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Câu 3: Có những cách nào làm thay đổi nhiệt năng của vật ? (1,0đ)
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Câu 4: Hãy giải thích vì sao khi đổ 50 cm3 nước vào 50 cm3 rượu, ta thu được hỗn hợp rượu và nước nhỏ hơn 100 cm3? (2,0đ)
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II. Bài tập : (4,0 điểm )
Câu 7: Một cái giếng sâu 8m. Anh An mỗi lần kéo được một thùng nước nặng 20kg mất 10 giây. Anh Bình mỗi lần kéo được một thùng nước nặng 30 kg mất20 giây. Tính
a) Công thực hiện của mỗi người.
b) Ai làm việc khỏe hơn?
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