The blame has been pinned, squarely and often, on inadequate oversight of U.S. financial institutions, which created ever more complex and risky mortgage instruments, lured people to buy homes they could not afford, and brought the economy crashing to the ground.
Motion on the Earth does not take place in a vacuum. When one thing moves, it moves through or across another. When a wheel turns on an axle, the two surfaces rub against one another. This is called dry friction. Grease can be used to separate the solid metal parts, but this just reduces the problem to layers within the grease sliding past one another.
In a disc-braking system the car's wheels are attached to metal discs, or rotors, that spin along with the wheels. The job of the caliper is to slow the car's wheels by creating friction with the rotors. The brake caliper fits over the rotor like a clamp. Inside each caliper is. a pair of metal plates bonded with friction material -- these are called brake pads.