Which statement correctly describes a concurrent force system?

Which statement correctly describes a concurrent force system?

• A. All forces are parallel.
• B. All forces have the same line of action.
• C. All forces are in the same plane.
• D. All forces act at the same point.

Answer: (D)

Concurrent forces are those whose lines of action cross at a single point. That means you can find a common point through which all their lines of action pass, even if the forces are applied at different spots on the body. Because of this, the resultant force can be considered to act at that intersection point, and the sum of moments about that point is zero. The statement that all forces act at the same point captures this idea directly: their lines of action meet at one shared point. If forces were merely parallel, their lines of action would never intersect, so they wouldn’t be concurrent. Being in the same plane describes coplanarity, not concurrency. Having the same line of action would be a special case where all lines coincide, which is not required for concurrency.

Concurrent forces are those whose lines of action cross at a single point. That means you can find a common point through which all their lines of action pass, even if the forces are applied at different spots on the body. Because of this, the resultant force can be considered to act at that intersection point, and the sum of moments about that point is zero.

The statement that all forces act at the same point captures this idea directly: their lines of action meet at one shared point. If forces were merely parallel, their lines of action would never intersect, so they wouldn’t be concurrent. Being in the same plane describes coplanarity, not concurrency. Having the same line of action would be a special case where all lines coincide, which is not required for concurrency.