9702 · 16.1
Internal energy
Ever wondered why a hot cup of tea feels warm, or why pumping up a bicycle tyre makes the pump warm? These everyday events are all linked to **internal energy**, a fundamental concept in physics. It's the hidden energy within a system, dictating how matter responds to heat and work. Get ready to uncover the microscopic world of particles and the powerful First Law of Thermodynamics! This pilot aligns with **Senpai Corner** A Level notes (2025-2027) for topic **16.1**.
Need to know
What you need to know
- **Definition**: Internal energy (U) is the sum of the random kinetic and potential energies of a system's molecules.
- **Kinetic Energy (KE)**: Related to the motion of particles. An increase in temperature leads to an increase in the average KE of the particles.
- **Potential Energy (PE)**: Related to the intermolecular forces between particles and their separation. PE changes significantly during a phase change (e.g., melting or boiling).
- **Temperature Link**: For any substance, increasing its temperature increases the random kinetic energy of its particles, thus increasing its internal energy.
Explanation
Internal energy
- **Definition**: Internal energy (U) is the sum of the random kinetic and potential energies of a system's molecules.
- **Kinetic Energy (KE)**: Related to the motion of particles. An increase in temperature leads to an increase in the average KE of the particles.
- **Potential Energy (PE)**: Related to the intermolecular forces between particles and their separation. PE changes significantly during a phase change (e.g., melting or boiling).
- **Temperature Link**: For any substance, increasing its temperature increases the random kinetic energy of its particles, thus increasing its internal energy.