• Stairs are inclined planes with steps that allow people to ascend and descend between levels in the house.stairs image by Mijakowska from Fotolia.com
  
  An inclined plane is a simple machine that is used in many ways every day around the house. Inclined planes are used to decrease the amount of force needed to move objects from a low point to a high point or from a high point to a low point. Rather than move an object straight up and down, an object travels up gradually because the points set apart from each other. The longer the ramp you form by spacing the two points apart, the less force you will need to lift the object.
  
  

Handicapped Accessibility

• Inclined planes in their most obvious form are used all throughout houses that are made accessible to the handicapped. Ramps are used so that wheelchairs can get into the door from the ground level. The height of the door from ground level determines the length of the ramp, or inclined plane, that will be used. According to guidelines by literamp.com, you need 6 inches of ramp length for every inch of rise, so a 6-inch rise would require 3 feet of ramp length. The ramp might consist of two inclined planes if the entrance is high above the ground. The inclined planes face in opposite directions, with a platform at the joint so a wheelchair can ascend the first plane, turn on the platform and then finish the ascent up the second inclined plane to the doorway. You might also see ramps placed throughout the home if the home has different levels.
  
  

Stairs

• Stairs might not be thought of as inclined planes because the actual steps camouflage the stringer that obviously identifies stairs as inclined planes. If you completely removed an entire staircase from your home, you would be left with a gap between the first and second floors. Stairs let us ascend that distance with less force than would be required to jump and then pull yourself up to the next floor. The flat steps allow you to use a steeper inclined plane because you have a place to put your foot. Without the steps, you would either slide down the steep inclined plane or you would need a much longer inclined plane that takes up the whole house. Spiral staircases require the less force to ascend than other stairs because the employ a much longer inclined plane that is wrapped in a spiral to reduce bulk.
  
  

Water Flow

• The sinks, tubs, showers and toilets throughout a home use inclined planes to encourage the water to flow down the drain. The bottoms of these objects are slightly inclined down toward the drain so that water is guided easily into the drain. Without this inclined plane, water would accumulate on the bottom so you would have to wait for the water to evaporate or guide the water into the drain yourself. Many homes have a dish rack next to the sink for drying hand washed dishes. The drain pan under the rack is elevated on one side and open on the opposite side next to the sink so that water that drips from the dishes can travel down this inclined plane and into the sink. Even the drain pipes are elevated to encourage the downward flow of water.