Engineering Mechanics

Concentrated Load in Mechanics Explained for Students

Stand on one leg on a wooden plank. Your whole body weight presses down through one small spot. The plank feels all of that force in a single place.

That is a concentrated load. It is a force that acts at a single point rather than being spread out. Concentrated loads are everywhere in engineering, from a person on a beam to a wheel on a bridge.

In this lesson you will learn what a concentrated load is, why it is also called a point load, its unit, and how it acts on a beam. You will also solve a simple example. By the end you will be able to spot and handle concentrated loads with confidence.

This follows the last lesson on internal forces. Quick recall: internal forces develop inside a body to resist the loads placed on it. Now we look at one common way loads are applied.

What Is a Concentrated Load?

A concentrated load is a force that acts at a single point on a body.

Instead of spreading over a length or an area, the whole force presses down on one small spot. Because the area is so small, we treat it as a single point in our calculations.

This is the simplest kind of load to handle. Since it acts at one place, you can show it with a single arrow and use it directly in your equations.

Why Is It Called a Point Load?

A concentrated load is also known as a point load because it acts at one point.

In real life, no force truly acts on a perfect point. A person's foot, a car wheel, or a bolt all press over a tiny area. But that area is so small compared to the beam or structure that we treat it as a single point to keep the maths simple.

So point load and concentrated load mean the same thing. Both describe a force pressing at one spot.

What Is the Difference Between Concentrated and Distributed Loads?

Difference Between Concentrated and Distributed Loads

Let us keep this short, since distributed loads get their own lesson next.

A concentrated load acts at one single point, like a person standing on one spot. A distributed load spreads over a length or an area, like sand poured evenly along a plank.

The easy way to remember it: a concentrated load is focused on one place, while a distributed load is shared over many places. We will explore distributed loads fully in the next lesson.

What Is the Unit of a Concentrated Load?

A concentrated load is a force, so its SI unit is the newton (N).

For larger loads in real structures, engineers often use the kilonewton (kN), where 1 kN equals 1000 N. So you might see a beam carrying a point load of 5 kN, which is 5000 N.

The direction is usually downward, since most loads come from weight. But a concentrated load can point in any direction, depending on the situation.

How Is a Concentrated Load Shown on a Beam?

On a beam, a concentrated load is drawn as a single arrow pointing in the direction of the force, placed at the exact point where it acts.

The arrow starts at the load point and usually points downward for a weight. Its length can represent the size of the load to scale. Next to the arrow, we write its value, such as 100 N or 5 kN.

concentrated load

This clear single arrow is what makes concentrated loads easy to work with. You always know exactly where the force acts.

Concentrated Load Example

Let us solve a simple beam problem with a concentrated load.

A beam of length 4 metres rests on two supports, one at each end. A concentrated load of 100 newtons acts at the exact centre of the beam. Find the reaction at each support.

Step 1. The total downward load is 100 N. Step 2. The load sits at the centre, so it is shared equally between the two supports. Step 3. Each support carries half the load. Step 4. Reaction at each support = 100 divided by 2 = 50 newtons.

So both supports push up with 50 N each. Together they balance the 100 N load, and the beam stays in equilibrium. Clean and simple, because the load acts at one point.

What Are Real Life Examples of Concentrated Loads?

Concentrated loads are all around you once you start looking:

  • A person standing at one spot on a footbridge.

  • A car wheel pressing down on a road or bridge deck.

  • A heavy machine bolted to the floor at its feet.

  • A hook carrying a bag at a single point.

  • A column resting on a beam at one location.

In each case, the force presses at one small place, so we treat it as a concentrated load.

Where Do Engineers Use Concentrated Loads?

Concentrated loads appear in almost every structural calculation.

Structural engineers model wheel loads on bridges as concentrated loads to check if the deck is safe. Mechanical engineers treat a bolted machine's feet as point loads on the supporting frame. Starting with concentrated loads makes it easy to find support reactions, which is the first step in designing beams and frames.

When many concentrated loads act together on a complex part, engineers use simulation to find the effect at every point. That skill is developed in the FEA with ANSYS course.

Frequently Asked Questions

Q: What is a concentrated load? A: A concentrated load is a force that acts at a single point on a body, rather than being spread over a length or area. It is also called a point load.

Q: Why is a concentrated load called a point load? A: Because it acts at one point. Real loads press over a tiny area, but that area is so small it is treated as a single point.

Q: What is the unit of a concentrated load? A: The SI unit is the newton (N). For large loads, engineers often use the kilonewton (kN), where 1 kN equals 1000 N.

Q: What is the difference between a concentrated and a distributed load? A: A concentrated load acts at one single point, while a distributed load spreads over a length or an area.

Q: How is a concentrated load shown on a beam? A: It is drawn as a single arrow at the exact point where it acts, pointing in the direction of the force, usually downward.

Key Takeaways

  • A concentrated load is a force that acts at a single point.

  • It is also called a point load.

  • Its SI unit is the newton, and large loads use the kilonewton.

  • It is shown as a single arrow at the load point on a beam.

  • A concentrated load at the centre of a simple beam splits equally between the two supports.

  • Concentrated loads are the easiest loads to work with in mechanics.

Quick Revision Box

  • Concentrated load: a force acting at a single point

  • Also called: point load

  • SI unit: newton (N); large loads in kilonewton (kN), 1 kN = 1000 N

  • Shown as: a single arrow at the exact load point

  • Centre load on a simple beam: each support carries half

Practice Corner

  1. In your own words, what is a concentrated load?

  2. Why is a concentrated load also called a point load?

  3. What is the unit of a concentrated load?

  4. A beam on two end supports carries a 200 N concentrated load at its centre. Find the reaction at each support.

  5. Give two real life examples of a concentrated load.

Answers

  1. It is a force that acts at a single point on a body rather than being spread out.

  2. Because it acts at one point. Even though real loads cover a small area, that area is treated as a single point.

  3. The newton (N), with the kilonewton (kN) used for larger loads.

  4. Each support carries half, so the reaction at each support is 200 divided by 2 = 100 newtons.

  5. A person standing on one spot of a bridge and a car wheel pressing on a road. Other correct answers are fine.

What's Next

Next we study the Distributed Load, a force that spreads over a length or an area, and how to handle it by turning it into a single equivalent force.

Conclusion

A concentrated load is the simplest load in mechanics. It acts at a single point, is shown as one arrow, and is measured in newtons. Learn to spot point loads and split them across supports, and you will have the foundation for solving beams, frames, and bridges throughout the course.

Want to practise these skills? Explore the free tools on the GaugeHow Learn Hub and test yourself with the Practice and MCQ tests.

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