Lesson: Moment of a Force about a Point in 2D: Vectors Mathematics

In this lesson, we will learn how to find the moment of a planar system of forces acting on a body about a point as a vector.

Lesson Plan

Students will be able to

express the moment of a force as a vector,
find the moment of a force about a point in 2D when given the force as a vector and the 2D coordinates of the relevant points using the cross product,
find the sum of moments of a system of forces in 2D when given the forces as vectors and the 2D coordinates of the relevant points using the cross product,
find unknown values when given the moment and the forces as vectors in 2D,
finding the length of the perpendicular between the line of action of the force and a point using the moment.

Lesson Presentation

Lesson Video

Lesson Explainer

Lesson Worksheet

Q1:

If the force is acting at the point , determine the moment of about the point .

Q2:

Given that force acts through the point , determine the moment about the origin of the force . Also, calculate the perpendicular distance between and the line of action of the force.

Q3:

End of is at and has midpoint . If the line of action of the force bisects , determine the moment of about point .