Câu 31. Một khối hợp kim làm từ đồng và thép có khối lượng là 1,5kg và đang ở nhiệt độ 200C. Biết rằng 20% khối hợp kim được làm từ đồng, nhiệt dung riêng của đồng và thép lần lượt là 380 J/kg. K và 460 J/kg. K. Tính nhiệt lượng cần thiết để làm nóng khối hợp kim trên đến 1200C? A. 66 600J. B. 126 000J. C. 151 200J D. 59 400J.

Suppose that two tanks, 1 and 2, each with a large opening at the top, contain different liquids. a small hole is made in the side of each tank at the same depth 1.57 m below the liquid surface, but the hole in tank 2 has 2.49 times the cross-sectional area of the hole in tank 1. (a) what is the ratio ρ1/ρ2 of the densities of the liquids if the mass flow rate is the same for the two holes? (b) what is the ratio rv1/rv2 of the volume flow rates from the two tanks? (c) at one instant, the liquid in tank 1 is 14.9 cm above the hole. if the tanks are to have equal volume flow rates, what height above the hole must the liquid in tank 2 be just then?

What happens when you slowly pulled the carboard?

Two manned satellites approaching one another at a relative speed of 0.550 m/s intend to dock. the first has a mass of 2.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. assume that the positive direction is directed from the second satellite towards the first satellite. (a) calculate the final velocity after docking, in the frame of reference in which the first satellite was originally at rest.(b) what is the loss of kinetic energy in this inelastic collision? (c) repeat both parts, in the frame of reference in which the second satellite was originally at rest. final velocity(d) loss of kinetic energy = ?