The glass fractures outward from the point of impact. The particles that make up the glass break apart and move upward.
The rock fractures you are describing are likely joint fractures. Joints are natural cracks or fractures that develop in rocks due to stress or cooling. When joints occur in parallel sets along flat surfaces, they are known as sheet joints or exfoliation joints.
head of the femur
False
Crack a result over prolonged time as it occur due to inter-relationship with the preceeding and succeding criteria whereas fracture occur suddenly when there is an external force applied over it.
Stress fractures
Most fractures of the humerus occur in the middle of the bone, around the area of the shaft known as the diaphysis. This is due to the vulnerability of this part of the bone to direct trauma.
avulsed fragment occurs when bone fragments are pulled from their normal position by forceful muscle contractions or resistance from ligaments. Segmental fragmented positioning occurs if fractures in two adjacent areas occur
They don't really occur in an exact spot it is always different. Sourcs: Science Teacher
Compression fractures can be caused by osteoporosis, trauma inflicted on the back, and tumors that have started in the bone. Tumors that occur in the spine also cause compression fractures.
osteoporosis
Fractures are broken bones. Most fractures occur from: * Sudden accelleration or decelleration -- car collisions, falls * Torsion -- sharp twists -- side car collisions etc. * Penetration trauma -- bullet wounds * Crushing or compression -- car acciddents, something falling on you * Repetitive Impact (jumping up and down for a few hours on a very hard surface can cause shin splints -- small, linear stress fractures).
Stress fractures