The convection of heat in air happens naturally because warmer air is less dense and rises, causing air circulation in many situations. But not always! Air can stratify, with warmer air up high and cooler air down low. With this model you can explore how convection works if the heat source is near the ceiling of a room. You can also compare it to conduction in the same setting.

Air circulates quickly and easily if there are temperature differences to drive its motion. This may be desirable in a room, but in insulated walls and ceilings air circulation is a problem, since it transfers heat. Explore the effect of multiple barriers on the amount of convection and apply this to how insulation should be designed.

Most buildings have leaky places where air can enter or escape -- around windows, ceiling openings like pipes, wires or chimneys, and construction joints such as where the wall meets the floor or the floor rests on the foundation. The size and location of these leaks strongly affects the heating and cooling load. Use this model to experiment with wall and roof leaks in a house with a heater where the air can circulate freely.

Explore how potential energy created by particles of varying charge is converted to thermal energy.

Visualize the electrostatic force that two charges exert on each other. Observe how changing the sign and magnitude of the charges and the distance between them affects the electrostatic force.

This resource consists of a Java applet and expository text. The applet is a simulation of the coupon collector problem, which consists of sampling from the first m positive integers, with replacement, until k distinct values are obtained. The parameters m and k can be varied. The random variable of interest is the size of the sample.

This resource consists of a Java applet and expository text. The applet is a simulation of the standard casino craps game. The random variables of interest are the winning under various bets.

Experiment with a simulated Crookes tube for qualitative results similar to Thomson's experiments in which the electron was discovered.

With your mouse, drag data points and their error bars, and watch the best-fit polynomial curve update instantly. You choose the type of fit: linear, quadratic, cubic, or quartic. The reduced chi-square statistic shows you when the fit is good. Or you can try to find the best fit by manually adjusting fit parameters.

DASHlink is a virtual laboratory for scientists and engineers to disseminate results and collaborate on research problems in health management technologies for aeronautics systems. Managed by the Integrated Vehicle Health Management project within NASA's Aviation Safety program, the Web site is designed to be a resource for anyone interested in data mining, IVHM, aeronautics and NASA.

Explore how the code embedded in DNA is translated into a protein. DNA transcription and mRNA translation are modeled.

Data Science is a growing field across all disciplines and grade levels. Use the assets in this collection to help learn valuable skills and concepts related to collecting, using, analyzing, and presenting data. The VDOE, Data Science Teachers, and WHRO Education collaboratively created this content.

Explore the effect of an electric field on the electron distribution of an atom.

Why do objects like wood float in water? Does it depend on size? Create a custom object to explore the effects of mass and volume on density. Can you discover the relationship? Use the scale to measure the mass of an object, then hold the object under water to measure its volume. Can you identify all the mystery objects?

This resource consists of a Java applet and expository text. The applet simulates rolling n dice. The random variables of interest are the sum of the scores, the maximum score, the minimum score, and the number of aces. The number of dice and the probability distribution that governs the dice can be specified. The applet illustrates various distributions and the central limit theorem.

This resource consists of a Java applet and expository text. The applet simulates the rolling of n dice. The number of dice and the probability distribution that governs the dice can be specified.

This resource consists of a Java applet and expository text. The applet simulates the experiment of rolling a die and then tossing a coin the number of times shown on the die. The die distribution and the probability of heads can be specified. The applet illustrates a two-stage experiment.

Explore how molecules can cross a cell membrane and learn about the nature of their movement. Set up the model with high oxygen and low carbon dioxide outside the cell and low oxygen and high carbon dioxide inside the cell. In which direction do the oxygen and carbon dioxide molecules move?

Explore the role of pore size in the diffusion of a substance across a membrane. Diffusion is the process of a substance spreading out from its origin. Molecules diffuse through random molecular motion. Diffusion is always happening, even when a system appears to have reached equilibrium, because molecules are always moving. Cells are selectively permeable, meaning that their membranes allow some substances to cross easily while others are unable to cross without assistance. Cell membranes are selectively permeable, in part because its pores are small, allowing the cell to prevent larger molecules from moving across the membrane.

Movement of ions in and out of cells is crucial to maintaining homeostasis within the body and ensuring that biological functions run properly. The natural movement of molecules due to collisions is called diffusion. Several factors affect diffusion rate: concentration, surface area, and molecular pumps. This activity demonstrates diffusion, osmosis, and active transport through 12 interactive models.