Kiểm tra đội tuyển HSG Lý 9

Trường thcs vĩnh tiến đề kiểm tra đội tuyển HSG
Môn vật lí 9 . Thời gian: 120 phút.
Họ và tên : ................................................................................................................

Đề bài:
Câu 1: Để đo khoảng cách từ Trái Đất đến một ngôi sao, người ta phóng lên ngôi sao đó 1 tia lade.
Sau 9 giây máy thu nhận được tia lade phản hồi về mặt đất (tia lade bật trở lại sau khi đập vào ngôi sao).
Tính khoảng cách từ Trái đất đên ngôi sao, biết vận tốc của tia lade là 300 000 km/s.
Câu 2: Lúc 4 giờ, hai xe cùng xuất phát từ 2 địa điểm A và B cách nhau 36km. Chúng chuyển động cùng chiều từ A đến B. Xe thứ nhất khởi hành từ A với vận tốc 56km/h, xe thứ hai khởi hành từ B với vận tốc 48km/h.
Tìm khoảng cách giữa 2 xe sau 45 phút xuất phát?
Hai xe gặp nhau lúc mấy giờ? Cách A bao nhiêu km?
Câu 3: Thả đồng thời 100g sắt và 500g đồng ở 250C vào 700g nước ở nhiệt độ 850C.
Tính nhiệt độ khi cân bằng nhiệt. Biết nhiệt dung riêng của sắt, đồng, nước lần lượt là:
c1 = 460 J/kg.độ; c2 = 380 J/kg.độ; c3 = 4200 J/kg.độ;
Câu 4: Tính lượng dầu cần để đun sôi 2 lít nước ở 200C đựng trong ấm bằng nhôm có khối lượng 200g. Biết nhiệt dung riêng của nước và nhôm lần lượt là c1= 4200 J/kg.độ; c2= 880 J/kg.độ, năng suất tỏa nhiệt của dầu
là q = 44.106 J/kg và hiệu suất của bếp là 30%
Câu 5 : Cho mạch điện có sơ đồ như hình vẽ. Biết: U = 10V, R1 = 2
, R2 =9
, R3 = 3
, R4 = 7
,
điện trở của vôn kế là RV = 150
. Tìm số chỉ của vôn kế.







Bài làm:
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