The concepts introduced are: work, conservative forces, potential energy, kinetic energy, mechanical energy, and Newton’s law of universal gravitation. A wrecking ball is converting gravitational potential energy into kinetic energy and back and forth. If released with zero speed, the wrecking ball should NOT swing higher than its height when it was released. Professor Lewin puts his life on the line by demonstrating this.

This lecture covers resistive forces such as air drag. It includes the viscous (linear in velocity) and pressure (quadratic in velocity) terms. Quantitative demonstrations with balloons and with ball bearings dropped in syrup are shown. He concludes with numerical calculations of air drag examples, also discussing the contribution of air drag to the quantitative experiments down earlier in the course with falling apples.

In this lecture, Professor Lewin displays how the conservation of mechanical energy can be used to derive the equation of motion for simple harmonic oscillators (SHO). In doing so he covers gravitational potential energy, equilibrium points where the net force is zero, parabolic potential energy, and circular potential energy.

In this lecture, bound and unbound orbits are discussed. Professor Lewin begins with a description of escape velocity, or the minimum speed required to escape the gravitational pull. Various sources of energy, energy storage, energy conversion, and the world’s energy consumption are discussed. Power, or the rate at which a force does work on an object, is central to the conversation. Professor Lewin concludes with a few words on global energy consumption and sources: although the US has about 1/30 of the world’s population, it accounts for 1/5 the global energy consumption. He considers harvesting solar radiation and nuclear power to fix this energy crisis.