If there's only one force applied to an object, then you can calculate
its value with Newton's second law of motion. The formula are . . .
Force = (object's mass) x (its acceleration) .
If there are two or more forces applied to the object, then the formula
tells you what their sum is when all of their magnitudes and directions
are combined into one force. But it can't tell you what any one single
force in the group is.