Forces cause accelerations, not velocities (objects will keep moving with constant velocity if the net force is zero). For every force there is always a second reaction force of the same amount but acting on a different object and in the opposite direction. Pressure is force distributed over an area. Bernoulli’s principle is the result of air flow at different speeds and different pressures and causes baseballs to curve and the lips of a trumpet player to buzz. Energy comes in many forms and the total amount of energy is conserved (we can’t create it or destroy it, only convert it from one type to another). When energy is converted from one form to another some of it has to end up in a less useful form (heat that generally isn’t useful; this is the second law of thermodynamics). Also, as you go through this book remember that: Science words have specific narrow definitions; any number you see in science is a measurement of something, unlike in math class; and the laws of physics are always true with no exceptions.