Within 4.0 s of liftoff, a spacecraft that is uniformly accelerating straight upward from rest reaches an altitude
of 4.50 X 102 m [up).
(a) What is the spacecraft's acceleration?

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.