How Heat and Work Change Energy

Miacademy & MiaPrep Learning Channel

This engaging video lesson provides a clear and practical introduction to the First Law of Thermodynamics, using real-world examples like the SR-71 Blackbird spy plane and hot air balloons to ground abstract physics concepts. The narrator explains the fundamental relationship between heat ($q$), work ($w$), and the change in internal energy ($ΔE$), demonstrating that energy is conserved and can only be transferred, not created or destroyed. The video breaks down the mathematical formula $ΔE = q + w$ and provides specific rules for determining positive and negative signs based on whether a system gains or loses energy. Key themes explored include the definitions of thermodynamic systems and surroundings, the conversion of heat into mechanical work, and the principle of conservation of energy. The video specifically focuses on the crucial skill of identifying sign conventions—understanding when heat and work values should be positive or negative in calculations. It walks students through multiple practice problems, moving from conceptual identification to calculating energy changes in kilojoules. For educators, this video is an excellent resource for high school chemistry or physics units on thermodynamics. It bridges the gap between conceptual understanding and mathematical application. The step-by-step problem-solving sections allow for natural pause points where students can attempt calculations before seeing the solution, making it ideal for direct instruction or flipped classroom models. The use of the SR-71 Blackbird as a hook effectively demonstrates how thermodynamic principles solve real engineering problems.