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.
Answer:
Most of the EM waves from the sun that reach Earth are infrared waves, visible light, and UV radiation.
Explanation:
I hope this helps! Have a good day!
How can one explain<span> and predict the </span>interactions between objects<span> and within a system of </span>objects<span>? ... through </span>electric or magnetic fields to illustrate the forces between objects and the changes in energy of the objects due to the interaction<span>. ... </span>Forces<span> at a distance are </span>explained<span> by fields (gravitational, </span>electric<span>, and magnetic) ...</span>
Muscles supply the force. They exert force by getting shorter (contracting).
A muscle can't get longer by itself. There needs to be another muscle
pulling in the opposite direction.
