• Three bodies of masses m1, m2 and m3 are in a straight line and m1 is between m2 and m3. Represent the interactions on a force diagram
gravitational forces that act on each one of them.

• Three bodies of masses ma, mb and mc lie at the vertices of a triangle
equilateral represent the interactions on a force diagram
gravitational forces that act on each one of them.

• Three electric charges + q1, + q2 and −q3 are in a straight line and q2 is between
q1 and q3. Represent the interactions on a force diagram
electrical devices that act on each one of them.

• Three electric charges −q1, + q2 and −q3 are at the vertices of a triangle
rectangle where q1 is at the vertex corresponding to the right angle.
Represent in a force diagram the electrical interactions that
they act on each one of them.

Indicate the meaning of the following notations: