# What is with this projectile simulation?

1. May 24, 2017

### sohjau

1. The problem statement, all variables and given/known data

I need to do a project based around this simulation (https://phet.colorado.edu/en/simulation/projectile-motion). I was playing around with it and am confused with how it even works. It seems to work fine with the exclusion of air resistance, but it seems off with it included. When air resistance is included and mass is increased, the projectiles's range and maximum height is increased as well. Why does this simulation do that? Also, what is the altitude variable for?

2. Relevant equations

3. The attempt at a solution

First of all, I want to note that in my course, I have neither learned nor will learn a single thing about air resistance. All of my knowledge about it is from a quick search on the internet. Mass should have practically no effect on an object's trajectory unless it is very great because it would pull Earth towards it. This simulation demonstrates that more mass would increase an object's range. Honestly, I have no idea what calculations it is making to determine the trajectory.

2. May 24, 2017

### PeroK

Air resistance is proportional to area and mass to volume. For two objects of the same shape and density, therefore, the larger one will be held back less.

Also, consider a solid sphere and a hollow sphere of the same size The air resistance will be the same force for both, but will have less effect on the heavier, solid sphere.