VPython - example - 模拟自由落体运动

本作品采用知识共享署名-非商业性使用-相同方式共享 3.0 Unported许可协议进行许可。允许非商业转载，但应注明作者及出处。

作者：liuyuan_jq

2011-04-10

Fromhttp://wiki.showmedo.com/index.php/PythonThompsonVPythonSeries

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from visual import *
scene.width = 400
scene.height = 300
scene.autoscale = 0
scene.range = (100,100,100)
scene.center = (0,40,0)
ball = sphere(pos=(0,100,0),radius=2)
ground = box(pos=(0,-1,0),size=(10,2,10))
gravity = 9.8   # m/s**2
seconds = 0 
dt = .01
finished = False           
while not finished:
    rate(100)   # go thru the loop no more than 100 times/s
    seconds += dt
    # position equation: y(t) = y0 + v0*t + .5 * a * t**2
    ballHeight = 100 - .5 * gravity * seconds**2
    ball.pos = vector(0,ballHeight,0)
    if ballHeight - 2 < 0:
        finished = True
        print "seconds to fall: " + str(seconds)

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