Let's estimate he can push down with a force about a quarter of his weight. If he weighs 200 pounds, this would result in a force of 50 pounds, or 225 N. We also know that the force of friction (F) between his feet and the asphalt depends on the force with which he pushes down (N) and the "coefficient of kinetic friction"(μ) between the soles of his shoes, which we will assume are made of rubber, and the pavement.
F = μN
The μ between rubber and asphalt varies between 0.5 and 0.8. Let's assume a value of 0.7. Therefore, solving for stopping distance, we get:
D = ½(2100kg)(18m/s)2/(0.7)(225N) = 2160 meters, or over 1.3 miles!
The situation might be improved if he exerted his full 200 pounds, or 900 Newtons, of force against the ground. In that case:
D = 1/2(2100kg)(18m/s)2/(0.7)(900N) = 540 meters (about a third of a mile)
However, the amount of torque exerted on his ankles and knees might make that a problematic proposition.
"A Slower Speed of Light is a first-person game prototype in which players navigate a 3D space while picking up orbs that reduce the speed of light in increments. Custom-built, open-source relativistic graphics code allows the speed of light in the game to approach the player's own maximum walking speed. Visual effects of special relativity gradually become apparent to the player, increasing the challenge of gameplay. These effects, rendered in realtime to vertex accuracy, include the Doppler effect (red- and blue-shifting of visible light, and the shifting of infrared and ultraviolet light into the visible spectrum); the searchlight effect (increased brightness in the direction of travel); time dilation (differences in the perceived passage of time from the player and the outside world); Lorentz transformation (warping of space at near-light speeds); and the runtime effect (the ability to see objects as they were in the past, due to the travel time of light). Players can choose to share their mastery and experience of the game through Twitter. A Slower Speed of Light combines accessible gameplay and a fantasy setting with theoretical and computational physics research to deliver an engaging and pedagogically rich experience."
Robert Karplus' Introductory Physics: A Model Approach is an innovative textbook, written by a brilliant, inspiring teacher and pioneer in physics teaching reform. The book originated the key ideas of the modeling approach for teaching physics. This approach has been further evolved, developed and implemented by David Hestenes and many others, including Gregg Swackhamer, Malcolm Wells and Jane Jackson. In cooperation with Karplus' widow, Elizabeth Karplus, Dr. Brunschwig edited and published the Second Edition of Introductory Physics in 2003. This site includes a variety of additional materials that Brunschwig has developed related to the Karplus textbook.Fernand Brunschwig is a member of the faculty at Empire State College. He is on sabbatical for 2007-08 at Columbia Teachers College in NY City. Current Contact Information:brunschwig@tc.eduColumbia Teachers CollegeScience Education, Box 210525 West 120th StreetNew York, NY 10027
College Ready Physics Standards: A Look to the Future
written by Patricia Heller and Gay Stewart
This document contains a set of K-12 educational standards for physics. This work is an extension of Advanced Placement standards to a full K-12 progression of physics concepts. There are five main standards each with a set of objectives, foundation knowledge statements, conceptual learning targets, and learning outcomes. The document also includes instructional guides for each of the standards and objectives to help teachers interpret and address the learning outcomes. These guides include common student difficulties and the content boundaries for each grade band, as well as example activities, questions, and problems.
Segment from the helicopter documentary "Straight Up!", showing power line maintenance being performed on live wires by a man outside a helicopter, using a type of Faraday cage.
Great for shielding and faraday cages.
Wild.
From a Japanese TV show - a real life example of adding vectors and relative motion. The truck is moving at 100km/hr and a ball is shot backwards at 100 km/hr, resulting in it coming to a complete stop.
"Arkansas Conceptual Electricity and Magnetism
Conceptual Inventory Construction and Self Testing Site
This site allows a visitor to test his or her conceptual knowledge of electricity and magnetism. Electricity and magnetism inventories can also be constructed and printed from the site. To begin testing your understanding of electricity and magnetism, select a topic to the left. To build a conceptual inventory, select the Conceptual Inventory Builder link to the left or click he"
J-Track 3D Satellite Tracking
We hope you enjoy J-Track 3-D. It should appear in its own window and begin loading a database of hundreds of satellites. What you will see is a plot in 3-dimensions showing the position of these satellites. If you are unable to view then a JAVA updagrade could be necessary. Be sure to try the "Satellite" pull-down menu to choose which satellite you wish to view.
How to interact with JTrack-3D; it has its own menu items for View, Satellite, and Options:
All About G ForcesWhat's behind gravity forces, and how much of them can we take?
By Peter TysonPosted 11.01.07NOVAA few summers ago I took my then nine-year-old daughter on a glider ride. Midway through, as we soared over a coastal landscape, I casually asked the pilot whether he could do any tricks. Without a word, he threw the plane into a dive. We were accelerating straight towards the ground. My daughter and I shouted and grabbed the armrests. Suddenly we were hit with that thrill-inducing pressure familiar from rollercoasters-tensed facial muscles, light-headedness, a sense of altered reality.
Photo caption: This is a streetcar in New Orleans traveling back towards The Quarter on St. Charles Ave. I held the camera against the window sill, making sure to divide the image equally between the inside and the outside. Shot with a Nikon D700 at .8 sec @ f/20, ISO 400, Nikkor 18.0-35.0mm f/3.4-4.5 lens set at 23mm.
This photo was submitted to National Geographic's 2012 Photo Contest (Places). Photographer Don Chamblee is 53 years old, and has enjoyed cameras all his life, but he didn't start to get serious until college. Now, at 53 years old, he takes photos professionally and works in stock and fine art photos. You can read more about Don at his website.
"Students will utilize conservation of mass-energy to explain how the annihilating collision of a proton and an anti-proton can produce a particle with six times the mass of either."
"The activity will help give students a kinesthetic feel for the inertia concept. This lab is a great way to provide students with an experience that can be very thoroughly discussed and analyzed."
"There are two types of information that one normally wishes to find from a velocity versus time graph. The first and simplest objective is finding the acceleration. The second is to find a position versus time graph that produced the velocity versus time graph.
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Over 90 Flash(tm) animations used during lectures and labs. Many do NOT contain descriptions in the animations because they are designed to be used in conjunction with a lecturer. Many are moviews while others are student centered explorations. Most of the these animations are in a Flash 5 format. This means they can be used in PowerPoint presentations by download the swf file and dragging it to your slide.
GPS is handy for finding a route, but it might be able to solve fundamental questions in physics too. An analysis of GPS satellite orbits hints that Earth is heavier than thought, perhaps due to a halo of dark matter.