CBSE Class 10 Answered

With clothes it is  necessary because they are porous and things can get stuck in the fabric, aggitation forces water through the clothes and moves new cleaner water to the area. Also the physical movement helps break up the molecules of whatever might be in your clothes which increases the surface area and allows for faster and more comlplete wash. There are more reasons, like to evenly spread the soap around which breaks up the dirt molecues and allows it to be washed away and not stick right back on the clothes.