The problem is asking to find the moment exerted by the 100 kN force about two points: point A and point B. The image shows a structure with the following details:

1. Point A is located at the top of the vertical member of the structure (6 meters above the horizontal member).
2. Point B is located at the far right end of the horizontal member.
3. The force of 100 kN is applied vertically upwards, 8 meters from point A (along the horizontal member).

General Approach to Finding the Moment:

The moment ($M$) exerted by a force about a point is given by:

$M = \mathbf{r} \times \mathbf{F}$ Where:

• $\mathbf{r}$ is the position vector from the point of interest to the point of application of the force.
• $\mathbf{F}$ is the force vector.
• The moment is calculated as the cross product of $\mathbf{r}$ and $\mathbf{F}$, and it results in a scalar (in 2D problems).

For simplicity, we calculate: $M = F \cdot d$ Where:

• $d$ is the perpendicular distance from the point of interest to the line of action of the force.
• $F$ is the magnitude of the force.

1. Moment about point A:

• The perpendicular distance from point A to the force is the direct horizontal distance, which is $12 \, \text{m}$ (since $8 + 4 = 12 \, \text{m}$).
• The force is $100 \, \text{kN}$ acting upwards.

The moment about point A is: $M_A = 100 \, \text{kN} \times 12 \, \text{m} = 1200 \, \text{kN} \cdot \text{m}$

Since the force creates a counterclockwise moment around point A, the moment is positive.

2. Moment about point B:

• The perpendicular distance from point B to the force is the horizontal distance of $8 \, \text{m}$.
• The force is $100 \, \text{kN}$ acting upwards.

The moment about point B is: $M_B = 100 \, \text{kN} \times 8 \, \text{m} = 800 \, \text{kN} \cdot \text{m}$

This moment is also counterclockwise around point B, so it is positive.

Final Answer:

• Moment about point A: $M_A = 1200 \, \text{kN} \cdot \text{m}$ (counterclockwise).
• Moment about point B: $M_B = 800 \, \text{kN} \cdot \text{m}$ (counterclockwise).

Would you like further details on any of the steps?

Here are some related questions:

1. How do we calculate the moment in 3D problems?
2. What happens if the force is not perpendicular to the lever arm?
3. How do different units (e.g., Newtons and meters) affect moment calculations?
4. Can you explain the right-hand rule for determining the direction of moments?
5. What is the difference between a moment and a torque?

Tip: When calculating moments, always ensure you use the perpendicular distance between the force and the point to avoid mistakes.