Paul Hewitt's "Figuring Physics" in the Feb. 2016 issue asked whether it would take a larger velocity change to stop a satellite in a circular orbit or to cause it to escape. An extension of this problem asks: What "minimum" velocity change is required to crash a satellite into the planet, and how does that compare with the…

Races between moving objects are an engaging way to teach dynamics to introductory physics students. One standard example consists in racing hollow and solid cylinders as they roll down an inclined plane. Another striking demonstration is a race between two marbles on side-by-side tracks that start and end together, but with one track taking a…

An ice hockey player can strike a puck at speeds up to about 45 m/s (100 mph) using a technique known as the slap shot. There is nothing unusual about the speed, since golf balls, tennis balls, and baseballs can also be projected at that speed or even higher. The unusual part is that the player strikes the ice before striking the puck, causing the…

While a mutually agreed-upon definition of STEM education remains elusive, there is no doubt that instructional models and ideas put forward with the STEM label have had a tremendous impact on thinking, debate, and practice in schools worldwide. At issue is the degree to which some or all the STEM disciplines must be taught in a concurrent or…

According to the Newtonian formula for a simple pendulum, the period of a pendulum is inversely proportional to the square root of "g", the gravitational field strength. Einstein's theory of general relativity leads to the result that time slows down where gravity is intense. The two claims look contradictory and can muddle student and…

Cooking is a common experience in preschool classrooms, where teachers provide hands-on opportunities with ingredients in the process of following standard recipes. What sets this story apart is the way that the teacher supports the children in designing their own cookie recipe in an authentic way, using experimentation and manipulation of cookies…

Traffic on motorways can slow down for no apparent reason. Sudden changes in speed by one or two drivers can create a chain reaction that causes a traffic jam for the vehicles that are following. This kind of phantom traffic jam is called a "jamiton" and the article discusses some of the ways in which traffic engineers produce…

A rattleback is a well-known physics toy that has a preferred direction of rotation. If it is spun about a vertical axis in the "wrong" direction, it will slow down, start rocking from end to end, and then spin in the opposite (i.e. preferred) direction. Many articles have been written about rattlebacks. Some are highly mathematical and…

Understanding how to interpret and manipulate large data sets is increasingly important today; however, this experience has been slow to trickle down to the typical undergraduate student. Here, we describe the implementation of a project-based learning experience that uses portable air sensors for the real-time measurement of carbon dioxide,…

Describes the construction of a demonstration apparatus to illustrate the law of strings by using the light from a television screen to slow down the apparent motion of the waves of a string. (MDH)

Presents an activity that demonstrates the effectiveness of flame retardants--substances added to combustible materials to slow down or hinder burning--that can be introduced when discussing combustion reactions or during a practical or everyday chemistry unit. (ASK)

Trends in animal production have moved the industry toward large confined animal feeding operations (CAFOs). These CAFOs concentrate large amounts of manure-based nutrients in relatively small areas, which increases the risk of nutrient loss to the surrounding environment. In response to water quality concerns, P-based manure application…