Which of these sentences are true about Energy?

Question

1 Energy in a system cannot be completely recycled.

2 Energy can be created and destroyed

Answer 1

Hi. 1.

Answer 2

1. Energy in a system is always completed recycled into other forms or heat. Did you mean to ask if energy in a real world system can be converted into another form or work with 100% efficiency? - in which case the answer for the macro world is no... there is always some heat loss.
2. Energy cannot be created or destroyed. It can be converted into matter and visa versa as old Albert with the wild hair first pointed out.

Answer 3

1 is true due to the thermodynamic law of entropy. There's always going to be losses.

2 is false. energy can neither be created or destroyed. Einstein found this famous relationship between energy and mass. E=mc^2. Mass cannot be created, unless of course you are God.

Answer 4

1st one is true;