Another name for these two words is "constant" and you want to have a "constant", because you want something to compare your experimental group to, to see whether data had changed or not. So you have placebos or a double- blind to compare your experimental group to it and also so you know you don't have a bias or anything in the study.
A higher frequency. I just got this answer on usa test prep.
the average kinetic energy of the particles in an object is directly proportional to its TEMPERATURE.
