Circular motion is what an object has if it is moving around and around and around and around and around and around and around and around and around in a path that is a circle.
The body senses whether it is upright or lying down or whether it is moving or standing still through the vestibular system, which is in the upper portion of the inner ear.
Explanation:
The gravitational force equation is the following:

Where:
G = Gravitational constant = 
m1 & m2 = the mass of two related objects
r = distance between the two related objects
The problem gives you everything you need to plug into the formula, except for the gravitational constant. Let me know if you need further clarification.
Liquids do not have a definite size and always take the shape of the container they're in.