The objective lens in a dvd player must move quickly to keep the laser beam focused on the disc's reflective layer. why must this lens have a very small mass?

This is important 1. what happens to the speed of molecules in water vapor when it condenses to form a liquid? (2 points) the molecules slow down. the molecules speed up. the molecules slow down and then speed up. the molecules speed up and then slow down. 2. how might human activities change to compensate for a decrease in water supplies? (2 points) humans might build a factory. humans might build drainage systems. humans might extract more water from the ground. human behavior does not change because of the water cycle. i'll be grateful if anyone can answer these 2 questions !

Most short-period comets do not have randomly oriented orbits because

If an electric circuit is not grounded it is best to reach out and touch it to provide the ground a.true or b.false