This document discusses two physics simulations. The first simulates gas properties and allows users to observe how different gas molecules move under varying gravity and see how pressure and temperature change when a box is opened. The second simulation models masses and springs, allowing users to experiment with springs under different gravitational conditions, view spring energy levels, and apply varying amounts of friction to analyze differences. Both simulations enable slowing down or pausing experiments for closer examination.

1. Simulation- Gas properties
http://phet.colorado.edu/en/simulation/gas-properties

2. Unique Feature
The movement of two different types of gas
molecules are clearly shown in this simulation.
Gas properties can be determine at different
gravity level and this will increase the collision of
gas particles.
The door of the box which filled in gas can be
open to test the pressure and temperature
changes.
The force of gas particles towards the wall of box
is shown by the action of the robot icon.

3. Modeling- Masses and Spring
http://phet.colorado.edu/sims/mass-spring-lab/mass-spring-lab_en.html

4. Unique Feature
Experiment can be repeated, paused, with slow
motion or stopped at any time.
Can find out the flexibility of spring at different gravity
in when the gravity is zero or even in Earth, Jupiter
and Moon.
Able to view the energy of the spring when weight is
applied to them.
Can apply the different friction on the spring to see the
differences