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答案找到了, 自己算出来的。。。。
送交者: eachus 2013月12月20日07:58:11 于 [世界军事论坛] 发送悄悄话
回  答: 有一物理问题请教大家 eachus 于 2013-12-20 00:42:09

How high can you jump on the Moon?


On the moon the acceleration due to gravity is gm=1.62m/s2. On earth, a person of mass m=75kg can jump 0.5mvertically. let acceleration path of 0.4 meters.  Find the height this person will reach when jumping on the moon, if the person is wearing nothing in both places. 



Kinetic energy at take-off = potential energy at peak height = work done.

On Earth

                        W = m * g * h = 75 * 9.8 * 0.5 = 368 J

           take-off speed: 

                       E = 1/2  m * v ^2     ==>   v =   (2 * 368 / 75) ^0.5 = 3.13 m/s


           acceleration on the jump: 

                      a = v ^2 / (2 s ) = 3.13 ^2 / (2 * 0.4) =  12.26 m/s^2

            this acceleration is net acceleration related to ground, after over come the Gravity g = 9.8.

                    total acceleration = a + g = 12.26 + 9.8 m/s^2  = 22.06 m/s^2


            exerted force: 

                F = m * a = 75 * (22.06) = 1654.5  Newton


We now move the experiment to the Moon

            the moon the acceleration due to gravity  g = 1.62 m/s^2


            exerted force is the same,  mass is the same, acceleration on the jump on the jump is the same : 

                F = m * a = 75 * (22.06) = 1654.5  Newton


            net acceleration related to the moon:

                a = 22.06 - 1.62 = 20.44   m/s^2

            

               potential energy at peak height = work done.

                W = m * a * s = 75 * 20.44 * 0.4

                P = m * g * h 

                m * a * s = m * g * h

                h = ( a * s )/ g = (20.44 * 0.4) / 1.62 = 5.04 m


if the person is wearing a spacesuit with mass m=100kg.


                 m * a * s = (m + 100) * g * h

                 75 * (20.44 * 0.4)  / (175 * 1.62) = h

                h =  613.2 / 283.5 =  2.16 m



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  简单的说一下 - eachus 12/20/13 (510)
      双腿做的工一样, - eachus 12/20/13 (474)
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