Investigate the difference in attractive force between polar and non-polar molecules by "pulling" apart pairs of molecules. While all molecules are attracted to each other, some attractions are stronger than others. Non-polar molecules are attracted through a London dispersion attraction; polar molecules are attracted through both the London dispersion force and the stronger dipole-dipole attraction. The force of attractions between molecules has consequences for their interactions in physical, chemical and biological applications.

Compare the change in potential energy when you separate molecules from each versus when you break molecules apart.

This well-designed experiment compares CO2 impacts on salt water and fresh water. In a short demonstration, students examine how distilled water (i.e., pure water without any dissolved ions or compounds) and seawater are affected differently by increasing carbon dioxide in the air.

An interactive applet and associated web page that demonstrate the concept of complementary angles (angles that add to 90 degrees). The applet shows two angles. You can drag the endpoints of each angle and the other angle changes so that they always add to 90 degrees. They are drawn in such a way that it is visually obvious that together they form a right angle, although they are separate on the page. The angle measure readouts can be turned off for class discussions. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

The intent is to provide a map-based framework, complete with animations showing the geologic evolution of the area to be visited, so that students can then better appreciate the observations made at the various stops along the way and see how they each relate to the other and the big picture.

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Before Ernest Rutherford's famous gold foil experiment in 1911, it was not known how the positive part of the atom was distributed. His experiment showed that if you shot positively charged particles at the atoms in a very thin sheet of gold foil, that very rarely, a particle would bounce back from the foil rather than going straight through it. Experiment with changing the distribution of positive charge and see how it affects the paths of positively charged particles moving near it.

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!

The heat conductivity of a solid material defines how fast heat will flow through it. You can probably think of several everyday examples of materials with high (fast) conductivity or low (slow) conductivity. This model illustrates the effect of different conductivities by placing different materials between a hot and a cold object and graphing the changing temperatures.

The rate of heat flow between two objects is proportional to their difference in temperature. One experiences this every day, with stoves, outdoor weather and touching things. If you touch something that's the same temperature as your hand, there's no heat flow at all. This model allows you to adjust the temperature difference between two objects and observe the graph of heat flow.

Heat flows through solids at rates measured by their conductivity. The rate of heat flow is also proportional to the thickness of the material. This model compares the rate of heat transfer between two objects when they are separated by walls of different thickness.

Experiment with conductivity in metals, plastics and photoconductors. See why metals conduct and plastics don't, and why some materials conduct only when you shine a flashlight on them.

Experiment with conductivity in metals, plastics and photoconductors. See why metals conduct and plastics don't, and why some materials conduct only when you shine a flashlight on them.

An interactive applet and associated web page that demonstrate the concept of congruent angles. Three angles are shown which always remain congruent as you drag any defining point on any angle. They all change together. This is designed to demonstrate that the angles are considered congruent even if they are in different orientations and the line segments making them up are different lengths. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

An interactive applet and associated web page that demonstrate the congruence of polygons. The applet presents nine polygons that are in fact congruent, but don't look it because they are reflected and rotated in various ways. If you click on one, it rotates and flips as needed, then slides over the top of another to show it is congruent. The web page describes how to determine if two polygons are congruent. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

An interactive applet and associated web page that demonstrate the concept of congruent triangles. Applets show that triangles a re congruent if the are the same, rotated, or reflected. In each case the user can drag one triangle and see how another triangle changes to remain congruent to it. The web page describes all this and has links to other related pages. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

This active demonstration investigates the law of conservation of momentum using a person on rollerblades and a thrown medicine ball.

This simulation shows the difference between Constant Velocity vs. Constant Acceleration هذه المحاكاة تبين الفرق بين السرعه الثابته والتسارع المستمر في الفيزياء

The simulation shows five different motions in which objects experience constant acceleration, starting from rest. Although each motion is different, the underlying physics is the same. What features of the simulation reinforce the idea that the physics is the same?

An interactive applet and associated web page that show how to construct a 30 degrees angle with a compass and straightedge. The animation can be single-stepped or run as a continuous movie. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.