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A large crate is placed on the bed of a truck but is not tied down. As the truck accelerates forward the crate slides across the bed until it hits the tailgate. Explain why this happens? If the driver slammed on his brakes what could happen to the crate?
What is inertia. The crate slides back to the end of the truck because it tries to stay at rest. When the driver slams on his breaks, the crate will slide up because it is still traveling at the velocity the truck was going. This is due to Newton's first law.