Ask mr brain...all will be explained

PUBLISHED : Friday, 19 November, 1999, 12:00am
UPDATED : Friday, 19 November, 1999, 12:00am

Why do some people experience motion sickness? Motion sickness is a syndrome which occurs in some people when they travel in a car, aircraft or ship or when they are engaged in activities accompanied by irregular motion.

It occurs when the body is subjected to accelerations of movement in different directions or under conditions where visual contact with the actual outside horizon is lost. For example, when one is in the interior cabin of a ship or aircraft.

Our sense of balance is maintained by a complex interaction of the inner ears, which monitor the directions of motion; the eyes, which monitor where the body is in space and also directions of motion; the central nervous system (the brain and spinal cord); muscle and joint sensory receptors, and skin pressure receptors.

Motion sickness begins in the inner ear. The motion causes changes in the semicircular canals of the inner ear, making it unable to maintain a state of equilibrium. The eyes and other systems mentioned above also send conflicting messages to the brain and the symptoms of mo tion sickness will appear. These include headache, dizziness, nausea, vomitting, perspiration and drowsiness.

Motion sickness can be treated by medications, which usually need to be taken half-an-hour before you travel, but prevention is the best cure. Do not read while travelling and do not sit in a seat facing backwards. Sit by the window of an aircraft and look outside. Sit in the front seat of the car and look at distant scenery. Go up to the deck of a ship and look at the horizon.

After a typhoon goes ashore, will it disappear? WINNIE AU DMHC Siu Ming Catholic Secondary School A typhoon is a mass of revolving moist air tens of kilometres high and hundreds of kilometres wide. Many develop over the warm Pacific Ocean.

Typhoons are like a heat engine that feeds on the latent energy from water condensing in rising moist air.

They can only survive over warm oceans where there is a readily available supply of moisture and always weaken over land. They require air flow that enables their 'engines' to work.