Razi

Friction is a force that opposes the motion of two objects in contact. It arises due to microscopic irregularities on the surfaces of the objects. The amount of friction depends on the roughness of the surfaces and how hard they are pressed together. Friction can be helpful, like when it allows us to walk without slipping, or it can be a hindrance, like when it slows down moving parts in machines. Rougher surfaces create more friction than smoother ones. Friction acts in the direction opposite to the movement or attempted movement of the objects. It can be reduced by using lubricants such as oil or water. There are different types of friction, including static friction (which prevents motion) and kinetic friction (which opposes motion). The force of friction is nearly independent of the contact area but proportional to the force pressing the surfaces together. Friction is essential in many everyday…

Small force is used to move or lift light things

1. moving a small toy

2. combing hair

3. writing

4. lifting a feather

5. opening an umbrella

1. Roots hold the plant in the soil, take in water and nutrients, and sometimes store food.​

2. Stems support the plant and move water, food, and minerals to all its parts.​

3. Leaves make food for the plant using sunlight,carbon dioxide, and water (photosynthesis).​

4. Flowers help plants make seeds by attracting insects and doing pollination.​

5. Fruits protect the seeds and sometimes help in spreading them.​

6. Each of these parts works together so the plant can live, grow, and make new plants.​

A force can be big or small. A small force is used to move light things, and a big force is used to move heavy things.

Eg:

1. small forces are used for moving a toy.

2. combing hair.

3. writing.

4. lifting a feather .

Seeing forces in a simple way means understanding that forces are pushes or pulls that cause things to move or change their motion. Forces make objects start moving, stop moving, or change direction. For example, when you kick a ball, you push it, and when you pull a rope in a tug-of-war, you pull it. So, a force can either push something away or pull it closer.​

To see forces smaller and deeper, we learn that the forces we feel, like pushing or pulling, actually come from interactions between tiny particles called atoms. At the smallest level, forces come from fundamental interactions between particles. These include electromagnetism, which explains why atoms push and pull on each other, like when you push something and feel resistance. Gravity, usually seen as a force pulling objects together, is explained by how mass curves space-time, causing objects to move as if pulled.​

In simple…

 Potential energy is like stored-up energy. Imagine you're sitting at the top of a slide. You aren't moving yet, but because of where you are, you have energy stored inside you—this is potential energy. It's energy ready to do something because of your position.

Kinetic energy is the energy of moving things. When you start sliding down, you're moving, and that moving energy is kinetic energy.

Electricity is like an invisible power that helps things work. It is made of tiny particles called electrons that move through wires. When these tiny particles move, they make lights turn on, TVs work, and toys run. For example, when you press a button to turn on a light, electricity flows through the wires to make the bulb shine. Electricity can also be found in nature like in lightning during a storm. So, electricity is the energy that helps power many things we use every day.​

1. Electricity is a kind of energy that makes lights, TVs, and many other things work.

2. It comes from tiny particles called electrons that flow like water through wires.

3. To make electricity work, there needs to be a complete circle or circuit for electrons to travel.

4. Batteries and power plants give electricity a push to move through the wires.

5. When the circuit is complete, electricity flows and makes things like bulbs light up or motors run.

6. Electricity travels very fast, almost as fast as light.

The video "What is electricity? | STEM kids" explains electricity as the movement or flow of electrons from one atom to another. Atoms, which are the building blocks of everything, have electrons that can move between them. This flow of electrons is called electric current. Some materials, called conductors, allow electrons to move easily, while others, called insulators, do not. To make use of electricity, a complete path or circuit is needed for the electric current to flow, such as using a battery, wires, and a light bulb to create a working electric circuit .

1. Natural Electricity: Electricity in nature, like lightning, occurs when charges build up in clouds and interact with opposite charges on the ground, creating a high-voltage electric discharge that is extremely hot, hotter than the surface of the sun.

2. Man-made Electricity: Electricity generated by humans can come from sources such as batteries, power plants, and renewable resources like…

Electricity is a form of energy caused by the movement of tiny particles called electrons.

Electrons have a negative charge and move from one atom to another, creating an electric current.

Electricity can be found naturally, such as in lightning, or it can be generated by people.

When electrons move through a conductor like a metal wire, electricity flows and powers devices.

Static electricity happens when electrons build up in one place and cause a sudden flow, like a spark.

Electricity needs a closed path called a circuit to flow and power things like lights and machines.

Thermal expansion is when objects get bigger as they get hotter. This happens because heat gives energy to the tiny particles inside them. With more energy, these particles vibrate and move around more vigorously. This increased motion pushes the particles slightly further apart. The combined effect is a measurable increase in the object's size. A great example is the gaps left in bridges to prevent them from buckling in the heat.

1. Definition: An electromagnet is a temporary magnet where the magnetic field is produced by an electric current.

2. Core Components: It typically consists of a coil of insulated wire (solenoid) wrapped around a core of ferromagnetic material (like iron).

3. Operation Principle: When current flows through the coil, it creates a magnetic field (Oersted's discovery). The core intensifies this field greatly.

4. Control: A key advantage is the ability to easily turn the magnetism on and off and vary its strength by controlling the electric current.

5. Applications: They are essential in devices like electric motors, speakers, heavy-duty lifting cranes, and high-tech equipment like MRI machines.

⚡Electrical Energy 

1. Electrical energy is the energy from moving electric charges.

2. It makes devices like bulbs, fans, and TVs work.

3. It is measured in joules (J) or kilowatt-hours (kWh).

4. It shows how much electricity is used.

5. Example: A heater uses electrical energy to produce heat.

About Electric Charge

1. Electric charge is a property of matter.

2. It is of two types – positive and negative.

3. Like charges repel each other.

4. Unlike charges attract each other.

5. Flow of charges is called electricity.

Mass

1. Mass is the amount of matter in an object.

2. It is always the same, anywhere in the universe.

3. Mass is measured in kilograms (kg).

4. It does not depend on gravity.

5. Example: A stone has the same mass on Earth and the Moon.

Physical Quantities (5 lines)

1. Physical quantities are properties that can be measured.

2. Examples: length, mass, time, temperature, current.

3. They are of two types: fundamental and derived.

4. Fundamental are basic, derived are made from them.

5. Each has a standard unit in the SI system.

 Light

1. Light is a form of energy.

2. It travels in straight lines.

3. It helps us to see objects.

4. The Sun, bulbs, and fire are sources of light.

Opaque objects (with light)

Sound is a form of energy made when things vibrate. These vibrations move through air, water, or solids as waves, and when they reach our ears, we hear them.

Density is how much mass is packed into a given volume.It is calculated as mass ÷ volume.A heavy stone has higher density than a light sponge of the same size.