Chuyển đọng nào sau đây có thể được coi là sự rơi tự di nếu đc thả rơi A. một chiếc lá
B. một tờ giấy
C. một hòn sỏi
D. một lông chim

What is the earliest point in the universe that we can observe? why can’t we see back further than this?

According to newton’s first law of motion, which force is expected to cause a body to accelerate?

Asatellite component is in the shape of a cube with 10cm edges, has an evenly distributed mass of 2 kg and one bolt hole at each of four corners. if the maximum predicted random vibration environment is 10 grms, what bolt size would be a good choice for restraint? what other factors might drive bolt size besides force/stress?