第 1 單元，第 1 課

Position and Motion位置與運動

背單字

reference point參考點
The school is our reference point.
position位置
The car’s position is 3 km north of the station.
reference direction參考方向
We chose east as the reference direction.
motion運動
The train is in motion relative to the platform.
displacement位移
After running a full lap, her displacement was zero.
speed速率
The cheetah’s speed is about 100 km/h.
average speed平均速率
Our average speed on the trip was 60 km/h.
velocity速度
The plane’s velocity was 800 km/h west.
vector向量
Velocity and force are vectors.
motion diagram運動圖
The motion diagram shows the cyclist speeding up.
distance-time graph距離—時間圖
The steep line on the distance-time graph shows high speed.

這課的重點字