接触力与非接触力
Contact & Non-Contact Forces
注意到有些力需要两个物体接触才能产生（接触力），而磁力即使不接触也能在距离之外起作用（非接触力）。
Notice that some forces need contact between two objects (contact forces) while magnetic forces can act at a distance (non-contact forces)
学习证据 / Evidence
- 将接触力定义为需要物体相互接触的力（如推力、拉力、摩擦力）。
- 将非接触力定义为不需要接触、能在距离之外起作用的力（如磁力）。
- 将不同的力的例子分为接触力和非接触力两类。
- Define contact forces as those needing objects to touch (e.g. push, pull, friction)
- Define non-contact forces as those acting at a distance (e.g. magnetism)
- Sort examples of forces into contact and non-contact categories
评估问题 / Assessment
{{name}}能解释为什么必须碰到球才能踢它，但磁铁不用碰到回形针就能把它吸起来吗？
Can {{name}} explain why you have to touch a ball to kick it, but a magnet can pull a paperclip without touching it?