I know speed is relative. But suppose we are in a rocket in space, far from another (relative to us) stationary object. Suppose we could accelerate our rocket at eg 100,000 km per second towards another object. Then I suspect that we are either losing energy and/or matter through our rocket engine, but instead a tremendous amount of energy will be released when we collide with the other object that we would otherwise be neutral about. And suppose we never encounter another object. Will we keep this (potential) energy forever?
Answer
The correct terminology:
– Potential energy: the energy that is proportional to the height in a gravitational field.
– Kinetic energy: the energy that is proportional to the square of the speed relative to an observer.
you mean kinetic energy here. If you approach an object by 100,000 you have a huge kinetic energy for an observer on that object. (From your own point of view you have no kinetic energy. That other object has huge kinetic energy).
When you collide with that object, the kinetic energy is suddenly reduced to zero for the respective observers, with the largest part being converted into heat.
If your rocket engine is not on, you will continue to fly at a constant speed (unless you bump into something). The kinetic energy is constant. this is called “inertia”.
If you have a rocket engine that is constantly accelerating you, your kinetic energy continues to increase.
Answered by
Engineer Bart Dierickx
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