Why a thin cane does hurt more?

 As our body is not a flat surface, whenever any part of the body is hit by a stick or rod it makes contact with only a small part of the skin depending on the diameter of the stick or rod. When hit with a thin cane, it hurts a lot because the flexible cane has a smaller diameter and contacts a thin strip of the skin on the body b wrapping around the surface. Since the force experienced per unit area is large, the cells under the area of contact are crushed causing either a swelling or bruise in that part of the body. On the other hand, a thick stick has a larger diameter and does not flex easily. When it hits the body the total area of contact is smaller and as the contact point is much flatter the force gets distributed over a large surface area thereby causing less pain.