Question

The force acting at a point \( A \) is shown in the figure. The equivalent force system acting at point \( B \) is:

• A. Force 3000 N in same direction and 6000 Nm clockwise moment
• B. Force 3000 N in opposite direction and 6000 Nm clockwise moment
• C. Force 3000 N in opposite direction and 6000 Nm counter clockwise moment
• D. Force 3000 N in same direction and 12000 Nm counter clockwise moment

Hint:

When shifting a force from one point to another, always include the equivalent moment generated due to the offset. Moment = Force × Perpendicular distance from the new point.

Answer 1

The Correct Option is A

Step 1: Understand the original force and position.
From the figure, a vertical force of 3000 N is acting downward at point \( A \), which is 2 meters above the horizontal beam. The horizontal distance from point \( B \) to the vertical force is 4 meters. Step 2: Transfer the force to point \( B \).
When transferring a force from one point to another, the same force can be applied at the new point if a moment is added equal to the moment generated by the force about that point. Step 3: Calculate the moment about point \( B \).
Moment = Force × Perpendicular Distance = \( 3000 \, \text{N} \times 2 \, \text{m} = 6000 \, \text{Nm} \) Since the force is acting downward at a point to the left of \( B \), it causes a clockwise moment about point \( B \). Step 4: Final equivalent force system at \( B \).
A 3000 N force in the same downward direction, and
A 6000 Nm clockwise moment.