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.
Friction is the force that causes resistance between two objects that are moving against each other. Lubricants are substances that reduce friction. These include oils, gels and waxes that create slick surfaces that move easily over one another. Some lubricants are dry. When talcum powder is applied to skin, it forms a dry lubrication that keeps skin surfaces from chafing through friction. Learn more about Motion & Mechanics