Daily Dose 005 | STATICS
How do you find the Magnitude of the Force in the arm of a crane?
Finding the magnitude of a force is one of those problem types that when worked out from a mathematical basis, is one thing, but when they are presented into a theoretically real life form, welp, that’s whole’nother.
Aside from the pure Mathematics of engineering, Statics is one of the most important concepts we must master when it comes to taking the FE Exam. We will need to translate our understanding from paper to concept, and back again come you exam day.
But it doesn’t need to trip you up – we are here to ensure it doesn’t.
In this short review and video, we get down with another FE Exam Practice Problem, this time in the subject of STATICS, specifically revolving around finding the MAGNITUDE OF A FORCE.
What is STATICS?
STATICS is an area of engineering mechanics that studies the EFFECTS and DISTRIBUTION of FORCES on objects which are at and remain at rest.
These forces are assumed and assessed as if no deformation of the object occurs, or in other words, the body is rigid.
Dynamics, on the other hand, deals with objects that do not remain at rest, while Mechanics of Materials takes cues from each of these subjects, dealing with objects that deform under loads and forces.
Finding the MAGNITUDE OF A FORCE is FUNDAMENTAL to the problems you will be dealing with on the FE EXAM, so let’s make sure that this skill is fully dialed for you.
How to go about finding the magnitude of a force?
The process of finding the magnitude of a force is pivotal in real-world engineering practice, helping us in designing load-bearing structures, calculating material strength requirements, and ensuring safety in bridges, buildings, and machinery.
Without a doubt, you will be presented a problem on your FE Exam where you will be asked to determine the magnitude of a force, here’s a step-by-step process to tackle it:
- Step 1: Define the Equilibrium Conditions
- Step 2: Break Down Forces into Components
- Step 3: Apply Newton’s First Law (Translational Equilibrium)
- Step 4: Solve for Unknown Forces
- Step 5: Check Units and Directions
- Step 6: Verify with Additional Equations
- Step 7: Validate the Solution
- Step 8: Consider Real-World Factors
- Step 9: Document the Results
Identify the system or structure in which you need to find the force’s magnitude. Ensure that the system is in a state of equilibrium, meaning that all forces and moments acting on it are balanced.
If the force is not already given in its components, break it down into its horizontal and vertical components using trigonometric principles if the force is at an angle.
For a system to be in translational equilibrium, the net force in both the horizontal and vertical directions must be zero. Write down the equilibrium equations based on Newton’s first law for both directions.
If the force whose magnitude you’re trying to find is part of the equilibrium equations, set up the equation and solve for the magnitude of the force. This may involve other known forces and angles between them.
Make sure the units of the calculated magnitude match the units of force (typically Newtons or pounds-force). Also, check if the direction of the calculated force aligns with your expectations based on the problem statement.
If the system has more than one unknown force, repeat steps 3 to 5 for each unknown force until all forces’ magnitudes are determined.
Ensure that the calculated forces satisfy all equilibrium conditions and constraints of the problem. The system should remain in static equilibrium with balanced forces and moments.
In practical engineering applications, account for factors like friction, material properties, and safety margins to ensure the calculated force aligns with real-world conditions.
Record the calculated magnitude of the force in your analysis documentation, specifying units and direction. If you are working a multi-step problem, this information will for continued analysis.
Check out the video to see an FE Exam Statics Practice Problem that deals with finding the magnitude of a force and how you can go about solving it in the most efficient manner.
As always, we are here to help, Prepineer