Force Systems - Examples & Applications

Mathematical Theory Examples

Example 1: Basic Resultant of Concurrent 2D Forces

Three forces act on a bracket: F1=100 NF_1 = 100\text{ N} at 3030^\circ, F2=150 NF_2 = 150\text{ N} at 120120^\circ, and F3=200 NF_3 = 200\text{ N} at 270270^\circ (measured counter-clockwise from the positive x-axis). Determine the magnitude and direction of the resultant.

Step-by-Step Solution

0 of 4 Steps Completed
1

Example 2: Intermediate Moment of a Force in 2D

A force of F=400 NF = 400 \text{ N} acts on the end of a lever of length L=2.00 mL = 2.00 \text{ m} at an angle of 60.060.0^\circ to the lever. Calculate the moment of the force about the pivot point.

Step-by-Step Solution

0 of 2 Steps Completed
1

Example 3: Advanced Resultant of a 3D Force System

Two forces act on a point: F1={30.0i+40.0j50.0k} N\mathbf{F}_1 = \{30.0\mathbf{i} + 40.0\mathbf{j} - 50.0\mathbf{k}\} \text{ N} and F2={20.0i+10.0j+30.0k} N\mathbf{F}_2 = \{-20.0\mathbf{i} + 10.0\mathbf{j} + 30.0\mathbf{k}\} \text{ N}. Find the resultant force vector and its magnitude.

Step-by-Step Solution

0 of 2 Steps Completed
1

Example 4: Resultant and Location of Coplanar Parallel Forces

Four vertical forces act on a horizontal beam of length 10.0 m10.0\text{ m}. The forces are F1=20.0 kNF_1 = 20.0\text{ kN} downward at x=0.00 mx = 0.00\text{ m}, F2=40.0 kNF_2 = 40.0\text{ kN} downward at x=3.00 mx = 3.00\text{ m}, F3=10.0 kNF_3 = 10.0\text{ kN} upward at x=6.00 mx = 6.00\text{ m}, and F4=30.0 kNF_4 = 30.0\text{ kN} downward at x=10.0 mx = 10.0\text{ m}. Determine the magnitude, direction, and line of action of the resultant force.

Step-by-Step Solution

0 of 3 Steps Completed
1

Example 5: Moment of a 3D Force about an Axis

A force F={10.0i+20.0j15.0k} N\mathbf{F} = \{10.0\mathbf{i} + 20.0\mathbf{j} - 15.0\mathbf{k}\}\text{ N} is applied at a point PP with position vector r={2.00i+3.00j+4.00k} m\mathbf{r} = \{2.00\mathbf{i} + 3.00\mathbf{j} + 4.00\mathbf{k}\}\text{ m} relative to the origin OO. Calculate the moment of the force about the origin.

Step-by-Step Solution

0 of 2 Steps Completed
1

Example 6: Equivalent Force-Couple System

A force F=500 NF = 500\text{ N} acts downward on a cantilever beam at a distance of 3.00 m3.00\text{ m} from the wall (point AA). Replace this force with an equivalent force-couple system at point AA.

Step-by-Step Solution

0 of 2 Steps Completed
1

Example 7: Concentrated Force of a Rectangular Distributed Load

A simply supported beam is subjected to a uniform distributed load of w=2.50 kN/mw = 2.50\text{ kN/m} over its entire length of L=8.00 mL = 8.00\text{ m}. Determine the magnitude and location of the equivalent concentrated force.

Step-by-Step Solution

0 of 2 Steps Completed
1

Example 8: Equilibrium of a Particle in 2D

A weight W=1000 NW = 1000\text{ N} is suspended by two cables, AA and BB. Cable AA is at an angle of 30.030.0^\circ to the horizontal, and Cable BB is at 45.045.0^\circ to the horizontal. Find the tension in both cables.

Step-by-Step Solution

0 of 2 Steps Completed
1

Case Studies: Conceptual Theory

Case Study 1: The Principle of Transmissibility in Cables

When a cable is used to pull a car out of a ditch, the force exerted by the winch is applied to the bumper of the car. According to the Principle of Transmissibility, we can treat this force as if it were applied anywhere along its line of action. Discuss why this is valid for the car as a whole, but not for the bumper itself.

Step-by-Step Solution

0 of 1 Steps Completed
1

Case Study 2: Couples and Steering Wheels

When a driver turns a steering wheel using both hands, they apply equal and opposite forces on opposite sides of the wheel. Explain this action in terms of force systems and why it is an ideal way to turn the wheel.

Step-by-Step Solution

0 of 1 Steps Completed
1

Case Study 3: Concentrated vs. Distributed Loads on Bridges

When designing a bridge, engineers must account for both concentrated loads (like a heavy truck parked on the deck) and distributed loads (like the weight of the concrete deck itself or a steady stream of traffic). Discuss why modeling loads as concentrated forces is often a simplification of distributed forces, and when it is appropriate to do so.

Step-by-Step Solution

0 of 1 Steps Completed
1

Case Study 4: Varignon's Theorem and Wrench Design

A mechanic is using a long wrench to loosen a stuck bolt. They can either push perpendicular to the handle at the very end, or they can push at an angle closer to the middle. Using Varignon's Theorem, explain how the total moment on the bolt relates to the components of the applied force.

Step-by-Step Solution

0 of 1 Steps Completed
1