A change in motion is proportional to the motive force impressed and takes place along the straight line in which that force is impressed.
-Sir Issac Newton
In the photo above when point 0 is not moving, then the three forces that act on it are in equilibrium. This means that the resultant force on the x-axis is zero and the same applies for the resultant force on the y-axis.
IBDP-1 HL Physics student, in the Physics Laboratory using a practical experiment to determine the effect of force on the mass of an object.
Newton's Second Law of Motion states that if an unbalanced force acts on a body, that body will experience acceleration (or deceleration), that is, a change of speed. One can say that a body at rest is considered to have zero speed, (a constant speed). So any force that causes a body to move is an unbalanced force. Also, any force, such as friction, or gravity, that causes a body to slow down or speed up, is an unbalanced force.