Amineral a. has a chemical formula. c. has a characteristic internal structure. b. occurs naturally. d. all of the above.

A15,000 kg rocket traveling at +230 m/s turns on its engines. over a 6.0 s period it burns 1,000 kg of fuel. an observer on the ground measures the velocity of the expelled gases to be −1,200 m/s.

Hydroelectricity provides about 7 percent of the electricity generated in the united states. (a) explain how a hydroelectric power plant converts energy stored in water into electricity. (b) identify two factors that determine the amount of electricity that can be generated by an individual hydroelectricity power plant. (c) describe the two main types of land-based hydroelectric power plants. (d) describe two economic advantages and two environmental disadvantages of hydroelectricity.

Because air contracts as it cools, the air pressure inside a freezer is typically lower than on the outside. why do ice cubes inside a freezer tend to shrink over time? the ice sublimes, and then the water vapor deposits as ice crystals on the sides of the freezer. the ice melts, and then the liquid freezes as ice crystals on the bottom of the freezer. the ice dissolves oxygen from the air, forming a denser crystalline matrix. the ice reacts chemically with carbon dioxide in the air, forming gaseous carbon compounds.