A roller coaster starts down hill at 15.3 m/s. Five and half seconds later, its speed is 42 m/s. Find the acceleration of the roller coaster.?

Which statement is the best definition of an atom? a) anything that has mass and occupies space. b) the smallest particle that has the properties of an element. c) a substance that cannot be broken down chemically into simpler substances. eliminate d) the smallest unit of a substance that exhibits all of the properties characteristic of that substance.