🧲 Day 2 Science: Forces & Magnets (力与磁)
🎧 Listen to the Lesson (听讲解)
Hello, Sisi! Today we’re going to learn about Forces & Magnets（力与磁）. This is one of the most important topics in PSLE Science!
📚 Key Vocabulary (重点词汇)
🔹 Part 1: What is a Force? (什么是力？)
A force（力） is a push（推） or a pull（拉） acting on an object.
Forces can:
- 🚀 Make a stationary object move（开始运动）
- 🛑 Make a moving object stop（停止）
- 🔄 Change the direction（改变方向） of an object
- 📏 Change the speed（改变速度） — faster or slower
- 🫳 Change the shape（改变形状） of an object
The unit of force is the Newton (N)（牛顿）.
🎮 Interactive Demo: See Forces in Action! (互动演示)
Click a button to see the force in action!
🔹 Part 2: Types of Forces (力的类型)
1. Frictional Force （摩擦力） ⭐⭐⭐
Friction（摩擦力） is a force that opposes motion（阻碍运动） between two surfaces in contact.
📝 Key Point: Friction always acts in the opposite direction（相反方向） to motion.
💡 Example (例题)
Q: Why is it harder to slide a box on a rough surface than on a smooth surface?
A: Because a rough surface（粗糙表面） has more friction（更大的摩擦力） than a smooth surface. The rough surface creates more resistance against the motion of the box.
2. Gravitational Force （重力）
Gravity（重力） is the force of attraction（吸引力） between objects. On Earth, gravity pulls everything downwards（向下）.
💡 Example (例题)
Q: A ball is thrown upwards. What force causes it to come back down?
A: The gravitational force（重力） of the Earth pulls the ball back down.
🎮 Interactive Demo: Gravity in Action! (重力演示)
Click “Drop” to see gravity in action!
🔹 Part 3: Magnets (磁铁)
A magnet（磁铁） is an object that produces a magnetic field（磁场） and attracts certain metals like iron（铁）, nickel（镍）, and cobalt（钴）.
Magnet Poles (磁极)
Every magnet has two poles（极）:
- 🧭 North Pole (N)（北极）
- 🧭 South Pole (S)（南极）
📌 Golden Rule of Magnets (磁铁黄金法则)
✅ Like poles REPEL（同极相斥） — N repels N, S repels S
✅ Unlike poles ATTRACT（异极相吸） — N attracts S
🎮 Interactive Demo: Magnets! (磁铁演示)
Click to see magnets attract or repel!
🔹 Part 4: Practice Questions (练习题)
Q1: What force pulls objects towards the Earth?
Q2: Two magnets with their North poles facing each other will:
Q3: Which surface has the MOST friction?
📝 Summary (本节总结)
- ✅ A force（力） is a push or a pull
- ✅ Friction（摩擦力） opposes motion
- ✅ Gravity（重力） pulls objects downwards
- ✅ Like poles repel（同极相斥）, unlike poles attract（异极相吸）