You find a rock that is about 20 grams large. This rock contains about 10 grams of Uranium-235 and 10 grams of the element it decays into (Thorium-231). The half life of Uranium-235 is 700 million years. How old is this rock?

An automobile steering wheel is shown. what is the ideal mechanical advantage? if the ama is 8, what is the efficiency of the steering wheel?

Scientist have use computer models to create a series of maps that show how susceptible coastal cities in island countries are to the sea rising at different levels.the map shows that a 1 meter rise would swap cities all along the us eastern seaboard. a 6-meter sea level rise with sub merge a large part of florida. thermal expansion has already raise the oceans 10 to 20 centimeters the most likely cause,directly and indirectly, for such a rise in sea level is

Aweather balloon has a volume of 52.5 liters at a temperature of 252 k. the balloon is released and rises to an altitude where the temperature is 295 k. how does this temperature change affect the gas particle motion?