Discover what controls how fast tiny molecular motors in our body pull through a single strand of DNA. How hard can the motor pull in a tug of war with the optical tweezers? Discover what helps it pull harder. Do all molecular motors behave the same?

In this interactive activity from ChemThink, learn about covalent molecules and how the VSEPR theory predicts the shapes of covalently-bonded molecules.

Try the new "Ladybug Motion 2D" simulation for the latest updated version. Learn about position, velocity, and acceleration vectors. Move the ball with the mouse or let the simulation move the ball in four types of motion (2 types of linear, simple harmonic, circle).

Try the new "Ladybug Motion 2D" simulation for the latest updated version. Learn about position, velocity, and acceleration vectors. Move the ball with the mouse or let the simulation move the ball in four types of motion (2 types of linear, simple harmonic, circle).

This video segment adapted from NOVA relates the dramatic story of vulcanologists trying to predict the timing of the cataclysmic eruption of Mount Pinatubo in the Philippines.

Learn about position, velocity, and acceleration graphs. Move the little man back and forth with the mouse and plot his motion. Set the position, velocity, or acceleration and let the simulation move the man for you.

This article describes the work of Hubert Staudigel and Cathy Constable, researchers from Scripps Institution of Oceanography who study Mt. Erebus, Antarctica's most active volcano.

Build your own system of heavenly bodies and watch the gravitational ballet. With this orbit simulator, you can set initial positions, velocities, and masses of 2, 3, or 4 bodies, and then see them orbit each other.

Build your own system of heavenly bodies and watch the gravitational ballet. With this orbit simulator, you can set initial positions, velocities, and masses of 2, 3, or 4 bodies, and then see them orbit each other.

Join a group of middle-school students on a visit to a laboratory at the Massachusetts Institute of Technology, where they experiment with "mystery mud" and learn about the relationships between magnetism, particle motion, and changes in the state of matter.

In this video lesson, the concept of momentum applied to hard-body collisions is explained using a number of simple demonstrations, all of which can be repeated in the classroom. Understanding Newton's Laws is fundamental to all of physics, and this lesson introduces the vital concepts of momentum and energy, and their conservation. Only some preliminary ideas of algebra are used here, and all the concepts presented can be found in any high-school level physics book. In terms of materials required, getting hold of large steel balls may not be easy, but large ball bearings can be procured easily. On the basis of what students have learned in the video, teachers can easily generate a large number of questions that relate to one's daily experiences, or which pose new challenges: for example, in a collision between a heavy and light vehicle, why do those inside the lighter one suffer less injury?

In this video adapted from NOVA scienceNOW, find out about the discovery of a new building material, the carbon nanotube, whose physical properties could theoretically enable the creation of a 22,000-mile elevator to space.

This article provides background information related to natural resources of the poles, and renewable and non-renewable energy.

Produce light by bombarding atoms with electrons. See how the characteristic spectra of different elements are produced, and configure your own element's energy states to produce light of different colors.

In this physics lab, students investigate the motion of different skateboarders pulled with various values of constant force. Using skateboarders of different masses and a variety of constant force values, students produce distance vs. time motion graphs for a number of skateboarding trials. Students may develop their own methods for setting up the lab and recording the necessary data. Following data collection, students analyze the data using Newton's second law and discuss differences between trials, the effects of friction, and possible sources of error in the experiment.

In this lesson designed to enhance literacy skills, an early astronaut's experiences teach students that Newton's third law of motion—for every action, there is an equal and opposite reaction—applies both on Earth and in outer space.

In this video segment adapted from NOVA, NASA learns hard lessons from the first American attempt to do work while "walking" in space. The video also explores Newton's third law of motion.

In this video segment adapted from NOVA scienceNOW, MIT engineer Dava Newman is working to replace today's bulky, inflated space suits with a radical, sleek design that may one day allow astronauts to walk easily on Mars.

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.

Start a chain reaction, or introduce non-radioactive isotopes to prevent one. Control energy production in a nuclear reactor! (Previously part of the Nuclear Physics simulation - now there are separate Alpha Decay and Nuclear Fission sims.)