The curved beam as shown on the figure is on x-y plane. A force F=80 N acts to point A.

a-) Write force Fas a vector.
b-) Calculate moment of the force vector about point O.
C-) What is the magnitude of the moment about point O?

a-) To write force F as a vector, we need to consider its magnitude and direction. Here, we know that the force F acts towards point A with a magnitude of 80 N.

So, the vector representation of force F would be F = 80 N directed towards point A.

b-) To calculate the moment of the force vector about point O, we can use the cross product of the position vector from point O to any point on the line of action of the force, and the force vector itself.

Let's assume the position vector from point O to point A is r. Since the line of action of the force passes through point A, we can take r as the vector from O to A.

The moment, M, is given by the formula:

M = r x F

where 'x' denotes the cross product.

c-) To find the magnitude of the moment about point O, we need to calculate the magnitude of the resulting vector from the cross product in step b.

M = |r x F|

The magnitude of a cross product is given by:

|r x F| = |r| * |F| * sin(θ)

where θ is the angle between the position vector r and the force vector F.

Since the position vector r is perpendicular to the plane of the figure and the force vector F, the angle θ would be 90 degrees, making sin(θ) equal to 1.

Thus, the magnitude of the moment about point O can be found by:

M = |r x F|= |r| * |F| * sin(θ) = |r| * |F|

To calculate the magnitude, we need the values of |r| and |F|. Unfortunately, without the specific geometry of the figure or additional information, we cannot determine the values for |r| and |F| or provide an exact numerical answer.

Please provide more details about the figure or any additional information so that we can calculate the magnitude of the moment about point O accurately.