It is the first one. But if you have this question you are not a little boy
Velocity
if you change direction, say turn around, so does your velocity
an increase in velocity is called accelleration
The lightbulb, the fire, and the Sun all create light from some energy source.
The Moon doesn't create light. The parts of it that the Sun shines on
are visible, the parts of it that the Sun doesn't shine on are not visible.
Just like a rock on the ground at night, the Moon must be illuminated
by a flashlight in order to be seen. The Sun is the flashlight.
The control group is the independent variable and the experimental group is the dependent due to change during the experiment. The experimental group will usually rely on another variable in the experiment for change.
The speed of the spacecraft in this orbit