Clothes Dryer Motion

## Question:

How do the drying machine work based on the effect of centripetal force? Is it true that there is no force called centrifugal force i.e. it is a virtual force? When we put the clothes in the drying machine, they initially lie at the bottom of the drum. Once we turn on the machine the clothes will be suspending inside the drum. How are they suddenly loose contact with the drum? When they are not touching the drum, how can they have forces acting on them?

Thanks!

The clothes are subject to the force of gravity and the force of the drum wall. Before the drum rotates these forces cancel themselves out with the clothes lying on the bottom as you say. When the drum begins to rotate, friction between the piece of clothing and the drum aided by the protrusions on the drum wall, cause the piece of clothing to be carried up the side of the drum. The centripetal acceleration provided by the drum forcing the piece of clothing into a curved path, tends to hold the clothing against the drum wall. At some point the centripetal acceleration is overcome by the component of gravity directed away from the drum wall so the clothing falls down to the bottom of the drum again to repeat the process.

Because there are usually several pieces of clothing in the dryer at the same time, there are always some falling from the upper half of the drum into the lower half. This creates the illusion that the clothes are suspended in the drum away from the wall. Try running the dryer with a single face cloth in it to see what I mean. It will ride up the drum wall to a point, then fall back to the bottom to be carried up again.

This information is brought to you by M. Casco Associates, a company dedicated to helping humankind reach the stars through understanding how the universe works. My name is James D. Jones. If I can be of more help, please let me know.

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