Simulating water

okay let's dive into the use of particles for simulating water before talking about how lots of particles move let's start by looking at how one particle moves if I drop a particle or a ping-pong ball it accelerates towards the ground we also saw this kind of motion in the animation topic notice that it bounces back up but not quite as high as it started it loses some energy during the balance and eventually when it loses all of its energy it stops now let's look at a ping-pong ball simulator where we model each ping pong ball using a virtual particle the virtual particle accelerates downward until it hits an obstacle and then it bounces back up only with a little less energy with this simulator we can control how big the particle is using this slider we can also control how strong the gravity is using this slider a small gravitational value similar to the gravity found on the moon causes the particle to fall more gradually a larger gravitational value like the gravity here on earth causes the particle to follow the more familiar ray and sending it to a very large gravitational value like on Jupiter mix a particle fall really quickly we can also control how much energy the particle loses during a balance by controlling its elasticity it describes a fraction of energy that is retained when the particle bounces us disa T is a number between zero and one a value of 1 means the particle loses no energy it'll bounce forever this is called perfect elastic collision and it's something that doesn't happen in real life a value of zero means the particle loses all of its energy in this case sticking to the floor intermediate values give the particle more realistic motion elasticity is also used to control the energy loss when particles hit each other if we set elasticity to zero then the particles will lose all energy when they collide like this similar to a pile of marbles and as we increase the elasticity we get something that looks more like rubber balls and of course you can also change the size of the part chuckles let's pause here so you can use the next exercise to get some experience with the range of particle behavior you can achieve by changing the particle size gravity and elasticity