Aisha wonders whether wind or water causes the most erosion. she set up an experiment in which she used a watering can to pour water down a pile of dirt. she then used a fan to blow wind on a second pile of dirt that is the exact same shape and size as the first pile of dirt. aisha then measured how the height of the dirt piles changed. she also drew pictures of how their shape changed. in this experiment, what was the dependent variable?

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.