- #1
Mad_Eye
- 69
- 0
hi.. once again my thoughts bumped into weird energy question, yet, very basic...
so say there is car, which mass is 1kg (yes, very realistic indeed), accelerating from 0 to 2 m/s.
to viewer on the ground the energy at start was 0 and in the end 2J, the work done by the engine to the car is 2J.
but now, and I'm quite sure most of you get the problem as soon as i say the next sentence, say I'm walking against the car direction in 1m/s speed. so for me, the initial speed is 1m/s and the final speed is 3m/s, as you can calc yourself, for me the work the engine did is now 4J.
we can get the same results if we use the W=F*S definition.
am i missing something? or does work depends on the viewer?
if so, does it not related to very practical things, such as the amount of fuel was burned and so on?
thank you very much indeed :D
so say there is car, which mass is 1kg (yes, very realistic indeed), accelerating from 0 to 2 m/s.
to viewer on the ground the energy at start was 0 and in the end 2J, the work done by the engine to the car is 2J.
but now, and I'm quite sure most of you get the problem as soon as i say the next sentence, say I'm walking against the car direction in 1m/s speed. so for me, the initial speed is 1m/s and the final speed is 3m/s, as you can calc yourself, for me the work the engine did is now 4J.
we can get the same results if we use the W=F*S definition.
am i missing something? or does work depends on the viewer?
if so, does it not related to very practical things, such as the amount of fuel was burned and so on?
thank you very much indeed :D