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The Inclined Plane
Inclined planes are all around us. Many places have a ramp along with stairs for handicapped people. You must have played on a slide in the park, that it also an inclined plane. Even a staircase is a modified inclined plane.
The inclined plane is a truly simple 'simple machine' and yet, indispensable to our life. So how does such a simple machine find a place in our complex world? First, the definition:
The Inclined Plane is a plane surface set at an angle, other than a right angle, against a horizontal surface.
What will it be if the angle is in fact a right angle? It will be a vertical plane!
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How it Works
You can think of the inclined plane as a vertical plane made partly horizontal. In other words, an inclined plane has both a horizontal component and vertical component.
It is easier to push an object up along an inclined plane rather than life it up vertically. When we want to lift an object upwards, the downwards acting force of gravity opposes it or resists it. We must apply an upwards force equal to the force of gravity in order to lift the object up. An inclined plane decreases this resistive force by increasing the distance over which we have to move it. The reduced resistance makes our work simpler.
To get a feel for this, consider this. You must have noticed that it is more difficult to cycle or walk up a steeper road than one with a gentler slope. The steeper road has a greater vertical component.
The figure on the right shows two inclinced planes, and a vertical plane in blue. The orange plane is steeper, but shorter and the green plane is gentler but longer. Both the inclined planes rise to the same height that the vertical plane does. So, a gentler slope makes our work easier but it increases the distance travelled.
- Gravity is a vertical force.
- Only a part of it acts in the direction of the inclined plane.
- Only this force has to be overcome for moving the object up the inclined plane.
- Gentler the slope, lesser the part of gravitational force that has to be overcome.
- Gentler the slope, greater the distance over which it has to be applied.
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The term Mechanical Advantage was introduced in the first article in this series. Let us see how it can be calculated for an inclined plane.
Mechanical Advantage for inclined plane = Length along the incline / Vertical height of the incline.
So, if the mechanical advantage is 10, then we need to provide a force only one tenth the weight of an object to push it up the incline. But we will also have to cover a distance that is 10 times longer than the vertical height it is raised to.