The concepts of net force and statics are also illustrated. The relationship of force, acceleration, and mass is illustrated with a variety of examples. The effects of friction on motion are shown using both sliding and falling objects. The notion that a force is a push or a pull is developed. A variety of everyday examples, such as bouncing are used to support this impulse-momentum concept.
Conservation of momentum is demonstrated with colliding carts on an air track.
Mechanical energy in its potential and kinetic forms is illustrated with demonstrations that include a bouncing dart, a pendulum, and a simple pulley system. The conservation of energy is illuminated using everyday examples and a hand-cranked electric generator. The concepts of torque, center of gravity, and center of mass are applied to balancing. Demonstrations include finding the center of gravity of irregularly-shaped objects, a weighted disk that rolls uphill, and a seesaw. The concept of rotational inertia is developed from a variety of everyday examples and demonstrations using weighted objects, and rolling cans filled with both liquids and solids.