Question

What are like and unlike parallel forces?

Answer 1

Parallel forces

1. As long as two forces are acting on a body in the same direction and are parallel to one another, they are said to be acting in parallel and are referred to as parallel forces. This is true regardless of the magnitudes of the two forces.

Like parallel forces

1. Like parallel forces are forces that are parallel and act in the same direction. If there are two forces $F_1$ and $F_2$, then the resultant force $R=F_1+F_2$.
2. Thus, like forces are in the same direction.

Unlike parallel forces

1. Unlike parallel forces are forces that are parallel and act in opposite directions. If there are two forces $F_1$ and $F_2$, then the resultant force $R=-F_1+F_2$ where the negative force is the force acting in the downward direction.
2. Similar to this, when two forces are acting on a body and they are acting in the opposite direction, they are known as, unlike parallel forces. It doesn't matter what magnitudes the two forces have as long as they are acting on the body in the opposite direction and parallel to one another.
3. Thus, unlike forces are in the opposite direction and parallel to each other.