There have been a lot of changes over the years to brake pad materials and manufacturing methods.
Andrew Markel discusses the computations humans make to apply the brakes on a vehicle, and how they can change based on hard or soft pedal, pulsation and vibration, or other factors.
Avoid heavy braking or panic stops for the first couple of hundred miles. Normal driving will usually seat in most brake pads just fine, provided the rotors are clean, relatively smooth (no excessive scoring or grooving) and flat (no warpage or pedal pulsations).
Spurred by the laws enacted by California and Washington, several other states such as New York, Hawaii, Rhode Island and Oregon drafted legislation over the past several years aimed at reducing brake pad pollution. However, the Copper-free Brake Initiative, in tandem with California and Washington’s existing laws, effectively made other state-specific laws unnecessary.
Friction is the force resisting the relative motion of elements sliding against each other. In the case of cars and trucks, it is the brake pads pushing against a rotor that changes kinetic energy into heat.