问题
问答题
如图所示，用细绳悬挂的重50N的物体静止在空中，画出它所受重力G的示意图．
答案
找到重心，在物体的几何中心处，重力方向竖直向下，大小为50N，如图所示：
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如图所示，用细绳悬挂的重50N的物体静止在空中，画出它所受重力G的示意图．
找到重心，在物体的几何中心处，重力方向竖直向下，大小为50N，如图所示：
．
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| Traffic rules help to keep order on the road. They also help to keep people 1 . The pedestrian (行人) has as many rules to 2 as the driver of a car. You should walk on the sidewalk (人行道) or at the side of the road. Always look 3 before you walk across the street. If you like riding a bike, don't ride in the middle of the road or run 4 red traffic lights. When you ride a bike with a friend, don't look around or talk. If you drive a car, you should 5 at the traffic lights. You must always 6 a seat belt (安全带). Without belts 7 the driver and the passengers may be badly hurt in a sudden accident. You may not need to take a bus, but 8 if you have to travel in one. Get on or get off a bus only when it comes to a 9 . When it is full, don't try to get inside 10 you may fall off. Traffic rules are also called Road Safety rules. The maxim (格言) for all road users is "Thinking about others". | ||||
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