42% of the population in the U.S. has tried marijuana at least once. Marijuana use is spread mostly among young people. Marijuana is usually taken in a cigarette. When you smoke it you feel relaxed or high. Marijuana affects people's memory, judgement, and perception. A short term effect of smoking it is that your heart rate will increase. The use of marijuana plays a part in some kind of cancer. You feel the affects of marijuana in your body 30 mins to 1 hour after smoking it. When you smoke marijuana you will seem dizzy and giggly. That means you will laugh for no reason.