# Lesson Worksheet: Moment of a Force about a Point in 3D Mathematics

In this worksheet, we will practice finding the moment of vector forces acting on a body about a point in 3D.

Q1:

True or False: If the force acts at point , then its moment in 3D space about point is given by .

• AFalse
• BTrue

Q2:

If a force is acting at a point , find the magnitude of the component of the moment of about the -axis.

• A106 units of moment
• B141 units of moment
• C260 units of moment
• D13 units of moment

Q3:

The moment of the force about the origin is , where and . Given that the force passes through a point whose -coordinate is 4, find the and coordinates of the point.

• A,
• B,
• C,
• D,

Q4:

If the force is acting at a point whose position vector is and the - and -components of the moment of the force about the origin point are 73 and 242 units of moment, respectively, find the values of and .

• A,
• B,
• C,
• D,

Q5:

Find the moment of the force about the origin point, given that , and is acting at a point whose position vector is with respect to the origin point, then determine the length of the perpendicular segment drawn from the origin point to the line of action of the force .

• A, length units
• B, length units
• C, length units
• D, length units

Q6:

A force acts at point . Find the moment of this force about the point .

Q7:

In the figure, if the forces and are acting on the point , where and are measured in newtons, determine the moment vector of the resultant about the point in newton-centimeters. • A
• B
• C
• D

Q8:

The forces and act along and , respectively, as shown in the figure. Given that , , and are a right system of unit vectors in the directions of , , and , respectively, find the sum of the moments of the forces about point in newton-metres. • A
• B
• C
• D

Q9:

In the figure, determine the sum of the moment vectors of the forces 86 and 65 newtons about in newton-centimeters. • A
• B
• C
• D

Q10:

A force of magnitude 6 N is acting on and is represented by a vector in a plane perpendicular to the -axis as shown in the figure. Determine its moment vector about in newton-centimeters. • A
• B
• C
• D

This lesson includes 23 additional questions and 198 additional question variations for subscribers.