You (50 kg) are standing on a floating log (200 kg). both are floating down a river at 1 m/s. the log points in the direction along the river. you walk in a direction that is down river for 5 seconds and your speed is 1.5 m/s as measured by a ground observer at the end of the 5 seconds.
a. what is the speed of the log at the end of the 5 seconds?
b. what is the average force between you and the log during those 5 seconds?
i think it'll be 7,000
carbon-14 is naturally created with the interaction of high-energy cosmic rays with atmospheric nitrogen. as part of the atmosphere, living organisms take in the carbon and incorporate this into living tissues. as long as the organism is alive and breathing, it keeps adding new carbon-14. when the organism dies, it stops gaining carbon-14 - or anything else, of course.
carbon-14 is slightly radioactive, with a half-life of about 5700 years. if we assume that the atmospheric production of carbon-14 has been steady for the last 100,000 years, we can calculate the approximate age of when the organism died by determining what percentage of carbon-14 still exists in the dead material.
paleo-archaeologists and anthropologists use this information when studying old cultures and civilizations.
well a basic explanation is that some elements have enough electrons to be considered stable. these elements do not need to react with other elements to gain more electrons. reactive elements are no where near stable; they respond with other elements in order to become stable. the more unstable, the harsher the reaction is.
it can't. acceleration is a change in velocity.