Position and Motion
位置和运动
Position is the place where an object is.
位置是物体所在的位置。
We can describe an object's position.
我们可以描述一个物体的位置。
For example, we can say, the ball is on the table.
例如，我们可以说，球在桌子上。
If the ball's position is changing, then the ball is in motion.
如果球的位置在变化，那么球在运动。
The ball is moving.
球在动。
Objects can move in different ways.
物体可以以不同的方式移动。
Some objects can move fast and others slow.
一些物体可以快速移动，而另一些物体可以缓慢移动。
An object can move in a straight line.
物体可以沿直线移动。
A ball can roll in a straight line.
球可以沿直线滚动。
A child on a swing moves forward and backward and also up and down.
荡秋千的孩子会前后移动，也会上下移动。
The swing moves in a curved line.
秋千呈曲线运动。
If you throw a ball to a friend, the ball will follow a curved line.
如果你把球扔给朋友，球会沿着一条曲线运动。
If you leap off a table, your motion will be up and away from the table and then down to the ground.
如果你从桌子上跳下来，你的动作将是向上离开桌子，然后下降到地面。
When you leap, you follow a curved line.
当你跳跃时，你沿着一条曲线。