Contents
Daily Dose 026 | Statics
How do you find the Moment generated about a point? Part 1
Determining the Moment generated about a point can get a bit tricky.
No longer are we dealing with rudimentary geometries, but rather, some quite complex configurations.
But we don’t need to punt these types of problems come exam day.
In fact, after running through the process just once, you will see just how simple they can be.
Understand this…
The FE Exam is designed to stretch us to the brink of our comfort zone.
And in doing so, it’s an exam testing how we operate under pressure just as much as it is one testing how well we grasp the fundamentals of engineering.
Much of the battle during this exam is making sure we stay calm and stable so that we can perform at our best.
This can only happen if you are putting yourself in difficult situations during practice.
We at Prepineer build our students up just as they do athletes leading up to a competition.
We will challenge and stretch you at all levels so that no matter what you see, you are prepared.
In this video, we dive in to a FE Exam Practice Problem, this time in the subject of STATICS, specifically revolving around GENERATING A MOMENT.
This is PART 1 of 2 for this particular problem.
Key Definition
What is a MOMENT?
A MOMENT is the measure of a force’s tendency to cause a body to rotate about a specific point or axis.
This is different from the tendency for a body to move, or translate, in the direction a force is acting.
In order for a moment to develop, the force must act upon the body in a way that causes it to begin to twist.
This occurs every time a force is applied so that it does not pass through the centroid of the body.
A MOMENT is due to a force not having an equal and opposite force directly along it’s line of action.
The Process
How can we find the Moment generated about a point?
So what will you do when asked to find the moment generated about a point?
A moment is a measure of the tendency of a force to rotate an object about a point or axis. It’s like the turning effect of a force. The farther away you apply the force from the point of rotation, the easier it is to turn or rotate the object.
In engineering, understanding moments helps us design everything from simple tools to complex structures like bridges and buildings, ensuring they can withstand various forces and rotations.
Here’s the general process to determine the moment generated about a point when you get this problem type of your FE Exam:
- Step 1: Identify the Force and the Point of Rotation
- Step 2: Determine the Position Vector
- Step 3: Measure the Magnitude and Direction of the Force
- Step 4: Calculate the Perpendicular Distance
- Step 5: Use the Moment Formula
- Step 6: Consider the Direction
- Step 7: Sum Up Moments
- Step 8: Interpret the Results
Find the force acting on the object and the point around which you want to calculate the moment.
Locate the position vector from the point of rotation to the point where the force is applied. This vector indicates the directed distance and position where the force acts relative to the point.
Identify the magnitude of the force and its direction. This information is often provided in the problem statement or can be calculated based on other given data.
Determine the perpendicular distance from the line of action of the force to the point of rotation. This distance is crucial for calculating the moment.
Apply the formula for the moment which is: Moment = Force × Perpendicular Distance. The moment is typically measured in Newton-meters (N-m), foot-pounds (ft-lbs), kip-feet (kip-ft).
Remember that moments can be clockwise or counterclockwise. This direction is important for understanding the overall effect on the object.
If multiple forces are acting, calculate the moment for each force, then sum them up, taking into account their directions.
Use the calculated moment to understand how and why the object will rotate or stay in equilibrium.
Following these steps will help you find the flow rate in an expanding pipe and understand the behavior of fluid flow in such systems. Always pay attention to the assumptions made and be mindful of units throughout the calculations.
Check out the video and see how to find the moment generated about a point in the most efficient manner come your FE Exam day.
As always, we are here to help, Prepineer
