Suhu, Kalor, dan Pemuaian | IPA Kelas 7 Bab 3 Kurikulum Merdeka - Lengkap

Introduction

This tutorial provides a comprehensive guide to the concepts of temperature, heat, and thermal expansion as discussed in the video by Miss Shinta. Aimed at seventh-grade students, this guide breaks down essential scientific principles, formulas, and processes related to these topics, making it easy to understand and apply.

Step 1: Understanding Temperature

• Definition: Temperature is a measure of how hot or cold something is, typically measured in degrees Celsius (°C) or Kelvin (K).
• Importance: It indicates the direction of heat transfer; heat flows from higher to lower temperatures.
• Measurement Tools: Familiarize yourself with thermometers, which are used to measure temperature.

Step 2: Grasping Heat

• Definition: Heat is a form of energy that transfers between systems or objects with different temperatures.
• Units of Measurement: Heat is measured in joules (J).
• Key Concept: The amount of heat energy transferred depends on the mass of the substance, the temperature change, and its specific heat capacity.

Step 3: Learning About Heat Transfer

Heat transfer occurs through three main processes:

Conduction

• Definition: The transfer of heat through direct contact between materials.
• Example: A metal spoon in a hot pot heats up because of direct contact with the hot liquid.
• Tip: Good conductors (like metals) transfer heat well, while insulators (like wood) do not.

Convection

• Definition: The transfer of heat through fluids (liquids and gases) by the movement of the fluid itself.
• Example: Warm air rising and cool air sinking creates convection currents in the atmosphere.
• Practical Application: This principle is used in heating systems and weather patterns.

Radiation

• Definition: The transfer of heat through electromagnetic waves, which can occur in a vacuum.
• Example: The warmth felt from sunlight is due to radiation.
• Common Pitfall: Remember that radiation does not require a medium (like air or water) to transfer heat.

Step 4: Calculating Heat Energy

Use the following formula to calculate heat energy:

[ Q = m \cdot c \cdot \Delta T ]

Where:

• ( Q ) = heat energy (in joules)
• ( m ) = mass (in kilograms)
• ( c ) = specific heat capacity (in J/kg·°C)
• ( \Delta T ) = change in temperature (in °C)

Example Calculation

1. If you have 2 kg of water (specific heat capacity = 4,186 J/kg·°C) and the temperature changes from 20°C to 100°C:
   • Mass (( m )) = 2 kg
   • Specific Heat Capacity (( c )) = 4,186 J/kg·°C
   • Change in Temperature (( \Delta T )) = 100°C - 20°C = 80°C
   • Calculate ( Q ): [ Q = 2 \cdot 4186 \cdot 80 = 669,760 \text{ J} ]

Step 5: Exploring Thermal Expansion

• Definition: Thermal expansion refers to the increase in volume of a substance when it is heated.
• Key Concept: Most materials expand when heated and contract when cooled.
• Real-World Application: This principle is applied in designing bridges and railways, which include expansion joints to accommodate changes in temperature.

Conclusion

Understanding temperature, heat, and thermal expansion is essential for grasping fundamental scientific concepts. Use this guide to review key terms and calculations, and apply these principles in real-world scenarios. For further exploration, consider conducting simple experiments that demonstrate heat transfer and thermal expansion, such as observing a metal ball and ring experiment or measuring temperature changes in different substances.