PhET Blog

We’re excited to publish our latest new simulation, Normal Modes:

Play with a 1D or 2D system of coupled mass-spring oscillators. Vary the number of masses, set the initial conditions, and watch the system evolve. See the spectrum of normal modes for arbitrary motion. See longitudinal or transverse modes in the 1D system.

Learn about Beer’s Law with this new simulation:

“The thicker the glass, the darker the brew, the less the light that passes through.” Make colorful concentrated and dilute solutions and explore how much light they absorb and transmit using a virtual spectrophotometer!

Check out the new tab, “Real Molecules,” in the Molecule Shapes or Molecule Shapes: Basics sims. By clicking on the tab, you can compare the VSEPR (Valence Shell Electron Pair Repulsion) model to real molecules.

Teachers, we need your input!

We have been experimenting with the addition of a new “Teacher” menu in our simulations. See “Teacher” along the upper left hand navigation in Molecule Shapes or Molecule Shapes: Basics. There you can change the background color to white.

Can you let us know how you might use this new Teacher menu and/or “white background” option in the comments below?

Watch your solution change color as you mix chemicals with water. Then check molarity with the concentration meter. What are all the ways you can change the concentration of your solution? Switch solutes to compare different chemicals and find out how concentrated you can go before you hit saturation!

Try our new Molarity sim. What determines the concentration of a solution? Learn about the relationships between moles, liters, and molarity by adjusting the amount of solute and solution volume. Change solutes to compare different chemical compounds in water.

Energy Skate Park: Basics is the next sim in our Basics series designed specifically for our middle-school audience. In this sim, learn about conservation of energy with a skater dude! Explore different tracks and view the kinetic energy, potential energy and friction as he moves. Build your own tracks, ramps and jumps for the skater.

We’ve added another sim to our Basics series with the new Molecule Shapes: Basics sim designed specifically for our middle-school audience. In this sim, you will explore molecule shapes by building molecules in 3D! Find out how a molecule’s shape changes as you add atoms to a molecule.

Learning goals that Molecule Shapes: Basics addresses include:

• Recognize that molecule shape is due to repulsions between atoms.
• Recognize that bonds are not fixed in place, but can rotate around in response to repulsions.

We are launching our Basics series with the new States of Matter: Basics sim designed specifically for our middle-school audience. In this sim, students can heat, cool and compress atoms and molecules and watch as they change between solid, liquid and gas phases.

Learning goals that States of Matter: Basics addresses include:

• Describe characteristics of three states of matter: solid, liquid and gas.
• Predict how varying the temperature or pressure changes the behavior of particles.
• Compare particles in the three different phases.
• Explain freezing and melting with molecular level detail.
• Recognize that different substances have different properties, including melting, freezing and boiling temperatures.

Try our new Balancing Act Sim to learn about balance, rotational equilibrium and torque. Play with objects on a teeter totter. Then test what you’ve learned by trying the Balance Challenge game.