Prader-Willi syndrome is a disease that is present from birth (congenital). It affects many parts of the body. People with this condition feel hungry all the time and become obese. They also have poor muscle tone, reduced mental ability, and underdeveloped sex organs. Causes Prader-Willi syndrome is caused by a missing gene on chromosome 15. Normally, parents each pass down a copy of this chromosome. The defect can occur in a couple of ways: The father's genes are missing on chromosome 15 There are defects or problems with the fatherâs genes on chromosome 15 There are two copies of the mother's chromosome 15 and none from the father; These genetic changes occur randomly. Persons who have this syndrome usually do not have a family history of the condition. Symptoms Signs of Prader-Willi syndrome may be seen at birth.
Definition of momentum for English Language Learners. : the strength or force that something has when it is moving. : the strength or force that allows something to continue or to grow stronger or faster as time passes.
Momentum describes how strong a moving thing is. Things that aren't moving have no momentum. Moving things have less momentum if they are light or moving slowly, and more momentum if they are heavy or moving fast. Because of momentum, a planet or a star that is moving in space will generally keep moving in the same direction unless something happens to push it another way. The Sun keeps going around the Milky Way, and the Earth keeps going around the Sun.