có 1 hỗn hợp vàng, kẽm, bạc. Hãy nêu cách tác 3 kim loại đó ra, cho biết:nhiệt độ nóng chảy của 3 chất vàng, kẽm, bạc lần lượt là 1064 độ C,420 độ C,960 độ C.

A33.1 g copper object is launched from a 1.5 m 30° steel incline positioned on the floor by being pulled up a string attached to a 50.0 g mass suspended vertically over a pulley. the object is projected towards a glass table where it lands when it is at the point along its trajectory with the lowest speed. it comes to a halt when it clears the opposite edge of the table. it then falls and lands on 9 physics texts each 5 cm thick that are stacked on the floor on the opposite side of the table. assume that the table does not have a ledge and the rectangular object experiences 0.05 n of air resistance as it falls towards the books. how far and how long did the object travel and how fast does it hit the books. assume that at the moment the copper object leaves the incline, the massless string and ideal pulley break off

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

The image shows a pendulum in simple harmonic motion the pendulum starts at a and swing to e