The heart beat can increase due to stress and exercise. There are many other factors that can increase heart rate.
moving around, emotion and what not
check you tube :P
Sometimes you can get scared,frustarated or upset and your heart rate will increase.
Cycling, swimming, running are three exercises that will increase the heart beat, open up the lungs, and increase the endurance and stamina.
Because the heart has to pump more oxygen than usual to your muscles
You can drastically increase your heart rate by smoking a bunch of crystal meth.
doing any excersice for 20 minutes or more, no less should increase your heart beat to the max. eg, jogging then sprinting.
Because everyones body reacts to fear with the "fight or flight" response with the brain producing adrenaline that speeds up your metabolism and your heart rate . I'm assuming your talking about a scary roller coaster ride or something to that effect.
they release a significnat amount of the hormone thottieness before and after get tired
It shouldn't. It may cause low blood pressure that can cause your heart rate to increase but that's a stretch.
Most video games will increase someone's heart rate. The main games that increase heart rate are racing (especially off-road or street racing) games, horror games, fast paced shooters, etc. Racing games like Need for Speed Series, Burnout Series, Flatout Series, Midnight Club Series, Motorstorm Series, etc increase it the most. Though if you play horror games like Alien vs. Predator 2, F.E.A.R, Doom Series, etc you can increase your heart rate considerably because of the constant spooks from bad guys or monsters or whatever jumping out the darkness at you suddenly. Violent shooters actually increase heart rate the least. Only a few shooters increase the heart rate significantly. An example would be the Brothers in Arms series.