If energy is neither created nor destroyed, how to objects 'get' energy?

gdec1

When we use energy, it doesn’t disappear. We change it from one form of energy into another. Converting one form of energy into another form always involves a loss of usable energy. In fact, most energy transformations are not very efficient. The human body is a good example. Your body is like a machine, and the fuel for your machine is food. Food gives you the energy to move, breathe, and think. But your body isn’t very efficient at converting food into useful work. Your body is less than five percent efficient most of the time. The rest of the energy is lost as heat. You can really feel that heat when you exercise! http://www.eia.doe.gov/kids/energyfacts/science/formsofenergy.html#conservation Aug 22 06, 9:01 PM

Gnomon

Energy is neither created nor destroyed, but it may be converted between a number of different forms: chemical energy is stored in chemicals such as the sugars in the food we eat gravitational potential energy is the energy possessed by objects because they are high up kinetic energy is the energy an object has because it is moving heat is another form of energy We can get energy by taking it from something else - if we eat food, we take in the energy with the food, remove it from the food and convert it either to chemical energy stored in our bodies, to kinetic energy by walking around or to heat, to keep us warm against the cold. If a car rolls down a hill, it converts its gravitational potential energy (by being high) into kinetic energy (as it moves). When it hits the wall at the bottom of the hill, the wall and the car all heat up slightly - the kinetic energy has been converted into heat. Aug 23 06, 4:14 AM

Baloo55th

Under 'normal' circumstances, energy and matter are not destroyed. However, Einstein's famous E=mc2 describes the interconnection of matter and energy. Energy CAN be created, but only by destroying matter (and a very little bit of matter can give a real heck of a lot of energy). Thus, there is conservation even there, for the total amount of energy+matter in the universe is not changed. As gdec says, when a transormation of energy takes place, there is a loss of usable energy. Some think that eventually (but don't worry about it just yet!) the energy level of the universe will be just that - level - instead of being 'lumpy' as it is at the moment. When that happens, basically nothing more WILL happen - nothing more can happen. Aug 23 06, 10:39 AM