Một vật có khối lượng m =20 kg được ném thẳng đứng lên cao. Ban đầu vật đứng yên. Lực cản của không khí FC = k. m (với hệ số cản là k=0,2). Hãy tìm quy luật chuyển dộng của vật và tính gia tốc của vật lúc t= 3s. Biết gia tốc trọng trường g= 9,81 m/s2

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blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.

the design of a ski jumping suit involves a trade-off between giving the skiers lift to get higher jumps and ensuring the skier does not face a lot of drag before the jump itself. an expansive suit may to lift the skier higher, but at the same time, it will also increase the air resistance. higher air resistance as the skier goes down the slope limits the speed of the jump. a big suit also increases the risk of losing balance or control, especially if there's a strong gust of wind. while technologically enhanced suits a lot, clothing is not the only factor in a ski jumper’s success. gathering speed while skiing down the slope, ensuring good speed on the ramp, and maintaining good body posture and form in the air all contribute to a ski jumper's success.