A rock falls from a vertical cliff that is 4. 0 m tall and experiences no significant air resistance as it falls. At what speed will its gravitational potential energy (relative to the base of the cliff) be equal to its kinetic energy?.

Which of the following ideas did greek philosopher democritus contribute to the atomic theory? a. each object is made up of one atom, which varies in size from very small to very large. b. matter is composed of only one kind of particle, which can be easily destroyed. c. every element has a specific type of atom, which remains the same size in all forms of matter. d. all matter is composed of small particles, which combine to make larger objects.