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1、一个坚直上抛的物体2次经过高度为h的点,在这2次通过该点之间的时间间隔为Δt。试求物体的初速度。 2、一个在河面光滑的冰上滑冰的人抛出一块质量m=0.5千克的石头。经过2秒钟,石头到达河岸,通过了距离l=20米。如果这个人的质量为M=60千克,那么他以多大的速度开始滑冰?摩擦力忽略不计。 3、一辆摩托车顺着水平公路行驶,要通过一个半径为R=4米的危险的转弯处。为使它关闭发动机后能顺着这个转弯处行驶,它应当有多大的速度?
1. An object that is thrown upright passes through the point of height h twice, and the time interval between the two passes through this point is Δt. Try to find the initial speed of the object. 2. A person skating on smooth ice on the river throws a piece of stone with mass m=0.5 kilograms. After 2 seconds, the stone reached the river bank and passed the distance l=20 meters. If the person’s mass is M=60 kilograms, then how quickly will he start skating? The friction is negligible. 3. A motorcycle runs along a horizontal road and passes a dangerous turn with a radius of R=4 meters. What speed should it have to make it turn off the engine and follow this corner?