Người ta thả một quả cầu nhôm khối lượng 300g đã được nung nóng tới 120¬0C vào một cốc nước ở 250C. Sau một thời gian, nhiệt độ của nước tăng đến 300C. a) Nhiệt độ của miếng nhôm ngay khi cân bằng nhiệt là bao nhiêu?
b) Tính nhiệt lượng do quả cầu tỏa ra. Biết nhiệt dung riêng của nhôm là 880J/kg. k
c. Tính khối lượng nước trong cốc. Biết nhiệt dung riêng của nước là 4200J/kg. k
Câu 2.

Explain earth's motion, using the terms "precession" and "rotation" in your answer.

Aplayground merry-go-round has a radius of 4.6 m and a moment of inertia of 200 kg-m2 and turns with negligible friction about a vertical axle through its center. a child applies a 26.0 n force tangentially to the edge of the merry-go-round for 15.0 seconds. if the merry-go-round is initially at rest, how much work did the child do on the merry-go-round?

Geologists get to play with chemistry, physics, and history! and what a history you will meet as youwork your way through the course. starting at the beginning, the textbook provides the scientifically acceptedstart of the and promises that you'll get to explore some of the evidence for that scientific view, later inthe semester. meanwhile, which is more nearly correct of the scientifically accepted view? a) the earth formed when the big bang caused older materials to fall together, about 14 billion years ago.b) the earth formed from the falling together of older materials, about 4.6 billion years ago.c) the earth formed in the big bang, about 6000 years ago.d) the earth is eternal, having been here forever and promising to be here forever.e) the earth was assembled by gigantic space beavers, which gnawed down the primordial tree of life andpiled its branches together to form the planet.