The earth atmosphere is divided into five layers. In the middle layer is where most foreign objects such as meteors Will burn up as they enter the atmosphere

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

30 points - when can a theory be modified if a new type of technology allows for new observations that raise new questions? a. immediately, while the questions about the theory are being asked b. after new hypotheses related to the theory are tested in experiments c. only after the new observations disprove all parts of the theory d. while scientists begin to think about how the theory could improve

Which is the correct symbol for an isotope of iodine with 53 protons and 78 neutrons?