Radio telescopes are said to "listen" to space because... 1. they monitor sound waves
2. they detect radio waves
3. they detect electromagnetic waves
4. they detect only aural EM waves

Does work output exceed work input when a machine is used? a) yes, it does, as machines create energy. b) it depends on the type of machine used. c) no, it doesn’t, as machines are inefficient. d) no, it doesn’t, as machines cannot create energy.