&引用；财产'；pos&x27；必须是向量"；运行VPython代码时出错

当我运行这段代码时，我得到一个错误“error:Property'pos'必须是一个向量”。我必须在某个地方写另一个向量吗？因为我在

grav_force = vector(0,-object.mass*grav_field,0)

这是我的全部密码

GlowScript 2.7 VPython

from visual import *

display(width = 1300, height = 1000)

projectile = sphere(pos = (-5,0,0),
                    radius = 0.1,
                    color = color.red,
                    make_trail = True)

projectile.speed = 3.2 # Initial speed.
projectile.angle = 75*3.141459/180 # Initial angle, from the +x-axis.

projectile.velocity = vector(projectile.speed*cos(projectile.angle),
                             projectile.speed*sin(projectile.angle),
                             0)

projectile.mass = 1.0
grav_field = 1.0

dt = 0.01
time = 0

while (projectile.pos.y >=0):
    rate(100)

    # Calculate the force.
    grav_force = vector(0,-projectile.mass*grav_field,0)

    force = grav_force

    # Update velocity.
    projectile.velocity = projectile.velocity + force/projectile.mass * dt

    # Update position.
    projectile.pos = projectile.pos + projectile.velocity * dt

    # Update time.
    time = time + dt

改变

到

见文件

也来自文件

GlowScript VPython和VPython 7与经典VPython 6有何不同

---

·矢量必须表示为矢量（x，y，z）或矢量（x，y，z），而不是（x，y，z）。

请在请求调试帮助时包含完整的错误回溯。您将速度定义为

对象，此时它是一个球体，而不是矢量。另外，不要使用
object
作为变量名，它是Python的内置组件之一。
projectile = sphere(pos = (-5,0,0), radius = 0.1,color = color.red, make_trail = True)

projectile = sphere(pos = vector(-5,0,0), radius = 0.1, color = color.red, make_trail = True)