The constant is the temperature of the air that the plants get.
The independent variable is the thing that YOU control. That's the amount of sunlight each plant gets.
The <em>dependent variable</em> is anything that's caused by changes in the independent variable. That's the growth of the plants.
<span>The shortening velocity refers to the speed of the contraction from the muscle shortening while lifting a load. Maximal shortening velocity is only attained with a minimal load. With a light load, the shortening velocity is at its Maximal shortening velocity. When the weight is heavy, the speed in which the muscle lifts the weight decreases in speed at a slower velocity.</span>