Examines the natural forces of gravity and friction that are constantly at work on Earth. Demonstrates the principles and forces that govern moving objects and how we use them to our advantage. Part 1 presents the law of universal gravitation and the forces of static and kinetic friction. Part 2 introduces Sir Isaac Newton's three laws of motion and the principles and forces that govern moving objects. Part 3 examines some of the different ways time can be measured, including sidereal and solar time. This section also examines why Earth has days and nights. Part 4 investigates jet engines, wing design, and special building materials that allow airplanes to take to the skies.
