Energy - Give and Take
Most recent answer: 10/22/2007
Q:
Where does the energy of an objects inertia come from. You can throw a ball, and provide a small amount of energy. Yet the ball will continue to move until stopped( which can be quite a distance ). And how is the ball interacting with the space around it to be moving in the first place?
- Mike Jr (age 28)
Beaverton, OR
- Mike Jr (age 28)
Beaverton, OR
A:
Mike -
The answer to your question depends largely on what example you're talking about, so let’s talk about the example you gave.
When you throw a ball, a lot more things happen than meet the eye. First of all, the ball gets its energy of motion from your hand which pushes it. The muscles in your hand and arm get their energy from a chemical reaction involving a compound called ATP. ATP is the way that your body stores the energy it gets from the food you eat.
Ok, so now the ball is flying through the air - why does it keep on moving? Well, the ball has a certain amount of energy. This is what determines how high up it is and how fast it’s going. The higher up it is, the more potential energy it has, and the faster it’s going the more kinetic energy it has. Energy can go back and forth between these two, but the total won’t change (unless the energy is transfered to something else). So the ball can be really high up and moving slowly or close to the ground and moving faster.
Now you’re probably going "Sure, so the ball will keep moving - that’s inertia. But we all know it won’t go forever - what stops it?" Well, it stops when it runs into something - when that happens, the energy that had been making it move is transfered into the thing it hit. The most obvious thing for it to hit is something big - the ground, another person’s hand, etc. Less obvious is the air itself! As the ball moves, it runs into a LOT of little air molecules. Sure, they’re really little so they don’t slow it down much, but it does make a difference. (This is especially convenient if you plan on taking up !)
Hope this helps!
-Tamara
The answer to your question depends largely on what example you're talking about, so let’s talk about the example you gave.
When you throw a ball, a lot more things happen than meet the eye. First of all, the ball gets its energy of motion from your hand which pushes it. The muscles in your hand and arm get their energy from a chemical reaction involving a compound called ATP. ATP is the way that your body stores the energy it gets from the food you eat.
Ok, so now the ball is flying through the air - why does it keep on moving? Well, the ball has a certain amount of energy. This is what determines how high up it is and how fast it’s going. The higher up it is, the more potential energy it has, and the faster it’s going the more kinetic energy it has. Energy can go back and forth between these two, but the total won’t change (unless the energy is transfered to something else). So the ball can be really high up and moving slowly or close to the ground and moving faster.
Now you’re probably going "Sure, so the ball will keep moving - that’s inertia. But we all know it won’t go forever - what stops it?" Well, it stops when it runs into something - when that happens, the energy that had been making it move is transfered into the thing it hit. The most obvious thing for it to hit is something big - the ground, another person’s hand, etc. Less obvious is the air itself! As the ball moves, it runs into a LOT of little air molecules. Sure, they’re really little so they don’t slow it down much, but it does make a difference. (This is especially convenient if you plan on taking up !)
Hope this helps!
-Tamara
(published on 10/22/2007)