An inclined plane is one of the six simple machines defined by early scientists that are used with reference to physics or mechanics. The other five are levers, pulleys, screws, wedges, and wheels and axles. These simple machines were designed to magnify or redirect force in such a way as to maximize the amount of work they could accomplish. Simply put, an inclined plane is an object that has a flat surface and is slanted at a fixed angle.
The mechanical advantage this machine provides is a reduced amount of force required to move objects between locations with different elevations. Without the plane, moving an object vertically would require much more force. Additionally, it can help move objects safely downward.
Using a child's slide on a playground as an example, if the child is on a platform above the ground and were to drop off of the platform straight down, he has a strong likelihood of getting injured. It's true that it would be faster, but it's definitely not safe. If a child uses a slide, an example of an inclined plane, then he will descend at a slower and safer rate. Similarly, if the child were to try to climb up to the top, it would require much more effort than if he walked up the slide.
An inclined plane has many applications and there are many examples of them in people's daily lives. Some examples are ramps, slides, chutes, knives, and hatchets. It may seem strange that a knife would be classified in this way, but a close look at the blade of a knife reveals the slope downward.
When an object is on an inclined plane, there are three main forces on it. These forces are normal force, gravitational force, and frictional force. While air resistance is a force on the object, it is usually not considered because it's typically negligible. The normal force is the force put on the object that is perpendicular (90°) to the incline. The gravitational force is the force pulling the object directly below it. Lastly, the frictional force is parallel to the plane. Rather than use trial and error, a person can predetermine whether an object can be moved up a plane by using a formula involving these three forces, the mass of the object, and the angle of the incline.