A Centripetal Acceleration.
When an object moves in a circular path, it accelerates toward the center of the circle due to the centripetal acceleration. This acceleration is necessary to keep the object moving in a curved path rather than in a straight line.
It accelerates.
Gravity
We call it a "semi-circle"
when an object moved in a circular path it accelerates toward the center of the circle as a result of
because if it had 4 straight lines instead, we would call it a rectangle.
A centripetal force - that is, a force that accelerates the body towards the center of the circle.
A semi-circle
Concentric Circles?
We call it a circle.
A circle with three dimensions is sphere.
a semi circle? common sense